<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.5a -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#Cover" roleURI="http://propanc.com/role/Cover" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#BalanceSheets" roleURI="http://propanc.com/role/BalanceSheets" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#BalanceSheetsParenthetical" roleURI="http://propanc.com/role/BalanceSheetsParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StatementsOfOperationsAndComprehensiveIncomeLoss" roleURI="http://propanc.com/role/StatementsOfOperationsAndComprehensiveIncomeLoss" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StatementsOfOperationsAndComprehensiveIncomeLossParenthetical" roleURI="http://propanc.com/role/StatementsOfOperationsAndComprehensiveIncomeLossParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StatementsOfChangesInStockholdersEquityDeficit" roleURI="http://propanc.com/role/StatementsOfChangesInStockholdersEquityDeficit" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StatementsOfCashFlows" roleURI="http://propanc.com/role/StatementsOfCashFlows" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPolicies" roleURI="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#GoingConcern" roleURI="http://propanc.com/role/GoingConcern" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#PropertyAndEquipment" roleURI="http://propanc.com/role/PropertyAndEquipment" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#DueToAndLoansFromFormerDirector-RelatedParty" roleURI="http://propanc.com/role/DueToAndLoansFromFormerDirector-RelatedParty" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#Loans" roleURI="http://propanc.com/role/Loans" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NotesPayableAndConvertibleNotes" roleURI="http://propanc.com/role/NotesPayableAndConvertibleNotes" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SeriesCPreferredStockAndSeriesCWarrants" roleURI="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrants" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#IncomeTaxes" roleURI="http://propanc.com/role/IncomeTaxes" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StockholdersEquityDeficit" roleURI="http://propanc.com/role/StockholdersEquityDeficit" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#CommitmentsAndContingencies" roleURI="http://propanc.com/role/CommitmentsAndContingencies" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#RelatedPartyTransactions" roleURI="http://propanc.com/role/RelatedPartyTransactions" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ConcentrationsAndRisks" roleURI="http://propanc.com/role/ConcentrationsAndRisks" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#DerivativeFinancialInstrumentsAndFairValueMeasurements" roleURI="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurements" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SubsequentEvents" roleURI="http://propanc.com/role/SubsequentEvents" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ReverseStockSplit" roleURI="http://propanc.com/role/ReverseStockSplit" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesPolicies" roleURI="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesTables" roleURI="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#PropertyAndEquipmentTables" roleURI="http://propanc.com/role/PropertyAndEquipmentTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NotesPayableAndConvertibleNotesTables" roleURI="http://propanc.com/role/NotesPayableAndConvertibleNotesTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SeriesCPreferredStockAndSeriesCWarrantsTables" roleURI="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrantsTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#IncomeTaxesTables" roleURI="http://propanc.com/role/IncomeTaxesTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StockholdersEquityDeficitTables" roleURI="http://propanc.com/role/StockholdersEquityDeficitTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#CommitmentsAndContingenciesTables" roleURI="http://propanc.com/role/CommitmentsAndContingenciesTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#DerivativeFinancialInstrumentsAndFairValueMeasurementsTables" roleURI="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurementsTables" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesDetailsNarrative" roleURI="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfTransactionExchangeRatesDetails" roleURI="http://propanc.com/role/ScheduleOfTransactionExchangeRatesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfAccumulatedOtherComprehensiveIncomeDetails" roleURI="http://propanc.com/role/ScheduleOfAccumulatedOtherComprehensiveIncomeDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfPropertyAndEquipmentEstimatedUsefulLivesDetails" roleURI="http://propanc.com/role/ScheduleOfPropertyAndEquipmentEstimatedUsefulLivesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfAnti-dilutiveSecuritiesExcludedFromComputationOfEarningsDetails" roleURI="http://propanc.com/role/ScheduleOfAnti-dilutiveSecuritiesExcludedFromComputationOfEarningsDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#GoingConcernDetailsNarrative" roleURI="http://propanc.com/role/GoingConcernDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfPropertyPlantAndEquipmentDetails" roleURI="http://propanc.com/role/ScheduleOfPropertyPlantAndEquipmentDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#PropertyAndEquipmentDetailsNarrative" roleURI="http://propanc.com/role/PropertyAndEquipmentDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#DueToAndLoansFromFormerDirector-RelatedPartyDetailsNarrative" roleURI="http://propanc.com/role/DueToAndLoansFromFormerDirector-RelatedPartyDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#LoansDetailsNarrative" roleURI="http://propanc.com/role/LoansDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfPromissoryNotesOutstandingDetails" roleURI="http://propanc.com/role/ScheduleOfPromissoryNotesOutstandingDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#NotesPayableAndConvertibleNotesDetailsNarrative" roleURI="http://propanc.com/role/NotesPayableAndConvertibleNotesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfConvertibleNotesDetails" roleURI="http://propanc.com/role/ScheduleOfConvertibleNotesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfKeyInputsWarrantLiabilityDetails" roleURI="http://propanc.com/role/ScheduleOfKeyInputsWarrantLiabilityDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SeriesCPreferredStockAndSeriesCWarrantsDetailsNarrative" roleURI="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrantsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfIncomeTaxProvisionDetails" roleURI="http://propanc.com/role/ScheduleOfIncomeTaxProvisionDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" roleURI="http://propanc.com/role/ScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#IncomeTaxesDetailsNarrative" roleURI="http://propanc.com/role/IncomeTaxesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SummaryOfWarrantActivityDetails" roleURI="http://propanc.com/role/SummaryOfWarrantActivityDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfShareBasedCompensationStockOptionsActivityDetails" roleURI="http://propanc.com/role/ScheduleOfShareBasedCompensationStockOptionsActivityDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#StockholdersEquityDeficitDetailsNarrative" roleURI="http://propanc.com/role/StockholdersEquityDeficitDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#CommitmentsAndContingenciesDetailsNarrative" roleURI="http://propanc.com/role/CommitmentsAndContingenciesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfRightOfUseAssetDetails" roleURI="http://propanc.com/role/ScheduleOfRightOfUseAssetDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfOperatingLeaseLiabilityDetails" roleURI="http://propanc.com/role/ScheduleOfOperatingLeaseLiabilityDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfFutureMinimumLeasePaymentsDetails" roleURI="http://propanc.com/role/ScheduleOfFutureMinimumLeasePaymentsDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#RelatedPartyTransactionsDetailsNarrative" roleURI="http://propanc.com/role/RelatedPartyTransactionsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ConcentrationsAndRisksDetailsNarrative" roleURI="http://propanc.com/role/ConcentrationsAndRisksDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfFairValueMeasurementsRecurringAndNonrecurringValuationTechniquesDetails" roleURI="http://propanc.com/role/ScheduleOfFairValueMeasurementsRecurringAndNonrecurringValuationTechniquesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails" roleURI="http://propanc.com/role/ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ScheduleOfDerivativeLiabilitiesAtFairValueDetails" roleURI="http://propanc.com/role/ScheduleOfDerivativeLiabilitiesAtFairValueDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SummaryOfChangesInFairValueOfLevel3WarrantLiabilityDetails" roleURI="http://propanc.com/role/SummaryOfChangesInFairValueOfLevel3WarrantLiabilityDetails" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#DerivativeFinancialInstrumentsAndFairValueMeasurementsDetailsNarrative" roleURI="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurementsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#SubsequentEventsDetailsNarrative" roleURI="http://propanc.com/role/SubsequentEventsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="ppcb-20260331.xsd#ReverseStockSplitDetailsNarrative" roleURI="http://propanc.com/role/ReverseStockSplitDetailsNarrative" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/Cover" xlink:title="00000001 - Document - Cover">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressesLineItems" xlink:label="loc_deiEntityAddressesLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressesTable" xlink:label="loc_deiEntityAddressesTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressesTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressesAddressTypeAxis" xlink:label="loc_deiEntityAddressesAddressTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_deiEntityAddressesTable" xlink:to="loc_deiEntityAddressesAddressTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain" xlink:label="loc_deiAddressTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiEntityAddressesAddressTypeAxis" xlink:to="loc_deiAddressTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain" xlink:label="loc_deiAddressTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiEntityAddressesAddressTypeAxis" xlink:to="loc_deiAddressTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_BusinessContactMember" xlink:label="loc_deiBusinessContactMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiAddressTypeDomain" xlink:to="loc_deiBusinessContactMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType" xlink:label="loc_deiDocumentType_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentType_30" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag" xlink:label="loc_deiAmendmentFlag_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiAmendmentFlag_30" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentDescription" xlink:label="loc_deiAmendmentDescription_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiAmendmentDescription_30" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentRegistrationStatement" xlink:label="loc_deiDocumentRegistrationStatement_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentRegistrationStatement_30" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentAnnualReport" xlink:label="loc_deiDocumentAnnualReport_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentAnnualReport_30" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentQuarterlyReport" xlink:label="loc_deiDocumentQuarterlyReport_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentQuarterlyReport_30" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentTransitionReport" xlink:label="loc_deiDocumentTransitionReport_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentTransitionReport_30" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentShellCompanyReport" xlink:label="loc_deiDocumentShellCompanyReport_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentShellCompanyReport_30" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentShellCompanyEventDate" xlink:label="loc_deiDocumentShellCompanyEventDate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentShellCompanyEventDate_30" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodStartDate" xlink:label="loc_deiDocumentPeriodStartDate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentPeriodStartDate_30" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_deiDocumentPeriodEndDate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentPeriodEndDate_30" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_deiDocumentFiscalPeriodFocus_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentFiscalPeriodFocus_30" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_deiDocumentFiscalYearFocus_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentFiscalYearFocus_30" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_deiCurrentFiscalYearEndDate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiCurrentFiscalYearEndDate_30" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber" xlink:label="loc_deiEntityFileNumber_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityFileNumber_30" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName" xlink:label="loc_deiEntityRegistrantName_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityRegistrantName_30" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey" xlink:label="loc_deiEntityCentralIndexKey_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityCentralIndexKey_30" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityPrimarySicNumber" xlink:label="loc_deiEntityPrimarySicNumber_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityPrimarySicNumber_30" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber" xlink:label="loc_deiEntityTaxIdentificationNumber_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityTaxIdentificationNumber_30" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="loc_deiEntityIncorporationStateCountryCode_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityIncorporationStateCountryCode_30" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1" xlink:label="loc_deiEntityAddressAddressLine1_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressAddressLine1_30" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine2" xlink:label="loc_deiEntityAddressAddressLine2_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressAddressLine2_30" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine3" xlink:label="loc_deiEntityAddressAddressLine3_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressAddressLine3_30" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown" xlink:label="loc_deiEntityAddressCityOrTown_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressCityOrTown_30" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince" xlink:label="loc_deiEntityAddressStateOrProvince_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressStateOrProvince_30" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCountry" xlink:label="loc_deiEntityAddressCountry_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressCountry_30" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode" xlink:label="loc_deiEntityAddressPostalZipCode_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityAddressPostalZipCode_30" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CountryRegion" xlink:label="loc_deiCountryRegion_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiCountryRegion_30" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode" xlink:label="loc_deiCityAreaCode_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiCityAreaCode_30" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber" xlink:label="loc_deiLocalPhoneNumber_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiLocalPhoneNumber_30" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Extension" xlink:label="loc_deiExtension_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiExtension_30" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_WrittenCommunications" xlink:label="loc_deiWrittenCommunications_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiWrittenCommunications_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SolicitingMaterial" xlink:label="loc_deiSolicitingMaterial_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiSolicitingMaterial_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementTenderOffer" xlink:label="loc_deiPreCommencementTenderOffer_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiPreCommencementTenderOffer_30" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementIssuerTenderOffer" xlink:label="loc_deiPreCommencementIssuerTenderOffer_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiPreCommencementIssuerTenderOffer_30" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle" xlink:label="loc_deiSecurity12bTitle_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiSecurity12bTitle_30" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_NoTradingSymbolFlag" xlink:label="loc_deiNoTradingSymbolFlag_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiNoTradingSymbolFlag_30" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol" xlink:label="loc_deiTradingSymbol_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiTradingSymbol_30" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName" xlink:label="loc_deiSecurityExchangeName_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiSecurityExchangeName_30" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12gTitle" xlink:label="loc_deiSecurity12gTitle_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiSecurity12gTitle_30" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityReportingObligation" xlink:label="loc_deiSecurityReportingObligation_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiSecurityReportingObligation_30" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AnnualInformationForm" xlink:label="loc_deiAnnualInformationForm_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiAnnualInformationForm_30" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AuditedAnnualFinancialStatements" xlink:label="loc_deiAuditedAnnualFinancialStatements_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiAuditedAnnualFinancialStatements_30" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="loc_deiEntityWellKnownSeasonedIssuer_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityWellKnownSeasonedIssuer_30" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityVoluntaryFilers" xlink:label="loc_deiEntityVoluntaryFilers_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityVoluntaryFilers_30" xlink:type="arc" order="44" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCurrentReportingStatus" xlink:label="loc_deiEntityCurrentReportingStatus_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityCurrentReportingStatus_30" xlink:type="arc" order="45" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInteractiveDataCurrent" xlink:label="loc_deiEntityInteractiveDataCurrent_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityInteractiveDataCurrent_30" xlink:type="arc" order="46" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFilerCategory" xlink:label="loc_deiEntityFilerCategory_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityFilerCategory_30" xlink:type="arc" order="47" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitySmallBusiness" xlink:label="loc_deiEntitySmallBusiness_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntitySmallBusiness_30" xlink:type="arc" order="48" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany" xlink:label="loc_deiEntityEmergingGrowthCompany_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityEmergingGrowthCompany_30" xlink:type="arc" order="49" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityExTransitionPeriod" xlink:label="loc_deiEntityExTransitionPeriod_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityExTransitionPeriod_30" xlink:type="arc" order="50" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentAccountingStandard" xlink:label="loc_deiDocumentAccountingStandard_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentAccountingStandard_30" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_OtherReportingStandardItemNumber" xlink:label="loc_deiOtherReportingStandardItemNumber_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiOtherReportingStandardItemNumber_30" xlink:type="arc" order="52" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityShellCompany" xlink:label="loc_deiEntityShellCompany_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityShellCompany_30" xlink:type="arc" order="53" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityPublicFloat" xlink:label="loc_deiEntityPublicFloat_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityPublicFloat_30" xlink:type="arc" order="54" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityBankruptcyProceedingsReportingCurrent" xlink:label="loc_deiEntityBankruptcyProceedingsReportingCurrent_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityBankruptcyProceedingsReportingCurrent_30" xlink:type="arc" order="55" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_deiEntityCommonStockSharesOutstanding_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiEntityCommonStockSharesOutstanding_30" xlink:type="arc" order="56" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentsIncorporatedByReferenceTextBlock" xlink:label="loc_deiDocumentsIncorporatedByReferenceTextBlock_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiDocumentsIncorporatedByReferenceTextBlock_30" xlink:type="arc" order="57" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_ContactPersonnelName" xlink:label="loc_deiContactPersonnelName_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityAddressesLineItems" xlink:to="loc_deiContactPersonnelName_30" xlink:type="arc" order="58" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/BalanceSheets" xlink:title="00000002 - Statement - Condensed Consolidated Balance Sheets">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember" xlink:label="loc_us-gaapNonrelatedPartyMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapNonrelatedPartyMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorMember" xlink:label="loc_PPCBFormerDirectorMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaapSeriesAPreferredStockMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesAPreferredStockMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaapSeriesBPreferredStockMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesBPreferredStockMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaapAssetsAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAssetsAbstract_180" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaapAssetsCurrentAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapAssetsCurrentAbstract_180" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Cash" xlink:label="loc_us-gaapCash_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_180" xlink:to="loc_us-gaapCash_180" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_GoodsAndServicesTaxReceivableCurrent" xlink:label="loc_PPCBGoodsAndServicesTaxReceivableCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_180" xlink:to="loc_PPCBGoodsAndServicesTaxReceivableCurrent_180" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_180" xlink:to="loc_us-gaapPrepaidExpenseCurrent_180" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_180" xlink:to="loc_us-gaapOtherAssetsCurrent_180" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_180" xlink:to="loc_us-gaapAssetsCurrent_180" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCosts" xlink:label="loc_us-gaapDeferredCosts_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapDeferredCosts_180" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseNoncurrent" xlink:label="loc_us-gaapPrepaidExpenseNoncurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapPrepaidExpenseNoncurrent_180" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsAssetsNoncurrent" xlink:label="loc_us-gaapDepositsAssetsNoncurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapDepositsAssetsNoncurrent_180" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset_180" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_180" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_180" xlink:to="loc_us-gaapAssets_180" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaapLiabilitiesCurrentAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaapAccountsPayableCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapAccountsPayableCurrent_180" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndOtherAccruedLiabilitiesCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapAccountsPayableAndOtherAccruedLiabilitiesCurrent_180" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrent" xlink:label="loc_us-gaapInterestPayableCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapInterestPayableCurrent_180" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableCurrent" xlink:label="loc_us-gaapLoansPayableCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapLoansPayableCurrent_180" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayableCurrent" xlink:label="loc_us-gaapNotesPayableCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapNotesPayableCurrent_180" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtCurrent" xlink:label="loc_us-gaapConvertibleDebtCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapConvertibleDebtCurrent_180" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapOperatingLeaseLiabilityCurrent_180" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaapDerivativeLiabilitiesCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapDerivativeLiabilitiesCurrent_180" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaapOtherLiabilitiesCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapOtherLiabilitiesCurrent_180" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstanding" xlink:label="loc_us-gaapWarrantsAndRightsOutstanding_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapWarrantsAndRightsOutstanding_180" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="loc_us-gaapEmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapEmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_180" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_180" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_180" xlink:to="loc_us-gaapLiabilitiesCurrent_180" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesNoncurrentAbstract" xlink:label="loc_us-gaapLiabilitiesNoncurrentAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapLiabilitiesNoncurrentAbstract_180" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermLoansPayable" xlink:label="loc_us-gaapLongTermLoansPayable_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesNoncurrentAbstract_180" xlink:to="loc_us-gaapLongTermLoansPayable_180" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityNoncurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesNoncurrentAbstract_180" xlink:to="loc_us-gaapOperatingLeaseLiabilityNoncurrent_180" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesNoncurrent" xlink:label="loc_us-gaapLiabilitiesNoncurrent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesNoncurrentAbstract_180" xlink:to="loc_us-gaapLiabilitiesNoncurrent_180" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapLiabilities_180" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:label="loc_us-gaapTemporaryEquityCarryingAmountAttributableToParent_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapTemporaryEquityCarryingAmountAttributableToParent_180" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaapCommitmentsAndContingencies_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapCommitmentsAndContingencies_180" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaapStockholdersEquityAbstract_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapStockholdersEquityAbstract_180" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaapPreferredStockValue_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapPreferredStockValue_180" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapCommonStockValue_180" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CommonStockIssuable" xlink:label="loc_PPCBCommonStockIssuable_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_PPCBCommonStockIssuable_180" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaapAdditionalPaidInCapital_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapAdditionalPaidInCapital_180" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax_180" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit_180" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValue" xlink:label="loc_us-gaapTreasuryStockValue_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapTreasuryStockValue_180" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_180" xlink:to="loc_us-gaapStockholdersEquity_180" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_180" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquity_180" xlink:type="arc" order="44" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/BalanceSheetsParenthetical" xlink:title="00000003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCConvertiblePreferredStockMember" xlink:label="loc_PPCBSeriesCConvertiblePreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesCConvertiblePreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaapSeriesAPreferredStockMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesAPreferredStockMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaapSeriesBPreferredStockMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesBPreferredStockMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:label="loc_us-gaapTemporaryEquityParOrStatedValuePerShare_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquityParOrStatedValuePerShare_110" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TemporaryEquityStatedValue" xlink:label="loc_PPCBTemporaryEquityStatedValue_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBTemporaryEquityStatedValue_110" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquitySharesAuthorized" xlink:label="loc_us-gaapTemporaryEquitySharesAuthorized_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquitySharesAuthorized_110" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquitySharesIssued" xlink:label="loc_us-gaapTemporaryEquitySharesIssued_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquitySharesIssued_110" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:label="loc_us-gaapTemporaryEquitySharesOutstanding_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquitySharesOutstanding_110" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityLiquidationPreference" xlink:label="loc_us-gaapTemporaryEquityLiquidationPreference_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapTemporaryEquityLiquidationPreference_110" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaapPreferredStockSharesAuthorized_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesAuthorized_110" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_110" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_110" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaapPreferredStockSharesOutstanding_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesOutstanding_110" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_110" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaapCommonStockSharesAuthorized_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesAuthorized_110" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesIssued_110" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaapCommonStockSharesOutstanding_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockSharesOutstanding_110" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CommonStockIssuableShares" xlink:label="loc_PPCBCommonStockIssuableShares_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBCommonStockIssuableShares_110" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TreasuryStockPricePerShare" xlink:label="loc_PPCBTreasuryStockPricePerShare_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBTreasuryStockPricePerShare_110" xlink:type="arc" order="15" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StatementsOfOperationsAndComprehensiveIncomeLoss" xlink:title="00000004 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Income (Loss)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StatementsOfOperationsAndComprehensiveIncomeLossParenthetical" xlink:title="00000005 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StatementsOfChangesInStockholdersEquityDeficit" xlink:title="00000006 - Statement - Condensed Consolidated Statements of Changes in Stockholders&apos; Equity (Deficit)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaapPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapPreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CommonStockIssuableMember" xlink:label="loc_PPCBCommonStockIssuableMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_PPCBCommonStockIssuableMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaapAdditionalPaidInCapitalMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAdditionalPaidInCapitalMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaapRetainedEarningsMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapRetainedEarningsMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember" xlink:label="loc_us-gaapTreasuryStockCommonMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapTreasuryStockCommonMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaapSeriesAPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesAPreferredStockMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaapSeriesBPreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesBPreferredStockMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockholdersEquity_100" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaapSharesOutstanding_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesOutstanding_100" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_100" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_100" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_100" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_100" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature" xlink:label="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature_100" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaapOtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_100" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLoss_100" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_100" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_100" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToDebtExchangeAgreement" xlink:label="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToDebtExchangeAgreement_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToDebtExchangeAgreement_100" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToDebtExchangeAgreement" xlink:label="loc_PPCBStockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToDebtExchangeAgreement_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToDebtExchangeAgreement_100" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement" xlink:label="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_100" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToWarrantExchangeAgreement" xlink:label="loc_PPCBStockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodSharesIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_100" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueReverseStockSplits" xlink:label="loc_PPCBStockIssuedDuringPeriodValueReverseStockSplits_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueReverseStockSplits_100" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesReverseStockSplits" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesReverseStockSplits_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesReverseStockSplits_100" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_100" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalOther" xlink:label="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalOther_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalOther_100" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DeemedDividendUponIssuanceOfPreferredStock" xlink:label="loc_PPCBDeemedDividendUponIssuanceOfPreferredStock_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBDeemedDividendUponIssuanceOfPreferredStock_100" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfUnits_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfUnits_100" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfUnits_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfUnits_100" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueIssuanceOfSeriesCPreferredStock" xlink:label="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfSeriesCPreferredStock_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfSeriesCPreferredStock_100" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:label="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalWarrantIssued_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalWarrantIssued_100" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueOfCommonStockForAlternateCashlessExerciseOfWarrants" xlink:label="loc_PPCBStockIssuedDuringPeriodValueOfCommonStockForAlternateCashlessExerciseOfWarrants_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueOfCommonStockForAlternateCashlessExerciseOfWarrants_100" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodSharesOfCommonStockForAlternateCashlessExerciseOfWarrants" xlink:label="loc_PPCBStockIssuedDuringPeriodSharesOfCommonStockForAlternateCashlessExerciseOfWarrants_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodSharesOfCommonStockForAlternateCashlessExerciseOfWarrants_100" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueIssuableShares" xlink:label="loc_PPCBStockIssuedDuringPeriodValueIssuableShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueIssuableShares_100" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodSharesIssuableShares" xlink:label="loc_PPCBStockIssuedDuringPeriodSharesIssuableShares_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodSharesIssuableShares_100" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RelativeFairValueOfWarrantGrantedInConnectionWithLoanPayableRelatedParty" xlink:label="loc_PPCBRelativeFairValueOfWarrantGrantedInConnectionWithLoanPayableRelatedParty_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBRelativeFairValueOfWarrantGrantedInConnectionWithLoanPayableRelatedParty_100" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DeemedDividendUponAlternateCashlessExerciseOfWarrants" xlink:label="loc_PPCBDeemedDividendUponAlternateCashlessExerciseOfWarrants_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBDeemedDividendUponAlternateCashlessExerciseOfWarrants_100" xlink:type="arc" order="31" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StatementsOfCashFlows" xlink:title="00000007 - Statement - Condensed Consolidated Statements of Cash Flows" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPolicies" xlink:title="999008 - Disclosure - NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/GoingConcern" xlink:title="999009 - Disclosure - GOING CONCERN" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/PropertyAndEquipment" xlink:title="999010 - Disclosure - PROPERTY AND EQUIPMENT" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/DueToAndLoansFromFormerDirector-RelatedParty" xlink:title="999011 - Disclosure - DUE TO AND LOANS FROM FORMER DIRECTOR - RELATED PARTY" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/Loans" xlink:title="999012 - Disclosure - LOANS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NotesPayableAndConvertibleNotes" xlink:title="999013 - Disclosure - NOTES PAYABLE AND CONVERTIBLE NOTES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrants" xlink:title="999014 - Disclosure - SERIES C PREFERRED STOCK AND SERIES C WARRANTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/IncomeTaxes" xlink:title="999015 - Disclosure - INCOME TAXES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StockholdersEquityDeficit" xlink:title="999016 - Disclosure - STOCKHOLDERS&#8217; EQUITY (DEFICIT)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/CommitmentsAndContingencies" xlink:title="999017 - Disclosure - COMMITMENTS AND CONTINGENCIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/RelatedPartyTransactions" xlink:title="999018 - Disclosure - RELATED PARTY TRANSACTIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ConcentrationsAndRisks" xlink:title="999019 - Disclosure - CONCENTRATIONS AND RISKS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurements" xlink:title="999020 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SubsequentEvents" xlink:title="999021 - Disclosure - SUBSEQUENT EVENTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ReverseStockSplit" xlink:title="999022 - Disclosure - REVERSE STOCK SPLIT" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesPolicies" xlink:title="999023 - Disclosure - NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Policies)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesTables" xlink:title="999024 - Disclosure - NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/PropertyAndEquipmentTables" xlink:title="999025 - Disclosure - PROPERTY AND EQUIPMENT (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NotesPayableAndConvertibleNotesTables" xlink:title="999026 - Disclosure - NOTES PAYABLE AND CONVERTIBLE NOTES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrantsTables" xlink:title="999027 - Disclosure - SERIES C PREFERRED STOCK AND SERIES C WARRANTS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/IncomeTaxesTables" xlink:title="999028 - Disclosure - INCOME TAXES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StockholdersEquityDeficitTables" xlink:title="999029 - Disclosure - STOCKHOLDERS&#8217; EQUITY (DEFICIT) (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/CommitmentsAndContingenciesTables" xlink:title="999030 - Disclosure - COMMITMENTS AND CONTINGENCIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurementsTables" xlink:title="999031 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NatureOfOperationsAndSummaryOfSignificantAccountingAndReportingPoliciesDetailsNarrative" xlink:title="999032 - Disclosure - NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfTransactionExchangeRatesDetails" xlink:title="999033 - Disclosure - SCHEDULE OF TRANSACTION EXCHANGE RATES (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaapPropertyPlantAndEquipmentLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember" xlink:label="loc_srtWeightedAverageMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtWeightedAverageMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyExchangeRateTranslation1" xlink:label="loc_us-gaapForeignCurrencyExchangeRateTranslation1_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaapForeignCurrencyExchangeRateTranslation1_70" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfAccumulatedOtherComprehensiveIncomeDetails" xlink:title="999034 - Disclosure - SCHEDULE OF ACCUMULATED OTHER COMPREHENSIVE INCOME (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfPropertyAndEquipmentEstimatedUsefulLivesDetails" xlink:title="999035 - Disclosure - SCHEDULE OF PROPERTY AND EQUIPMENT ESTIMATED USEFUL LIVES (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaapPropertyPlantAndEquipmentLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaapPropertyPlantAndEquipmentTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaapMachineryAndEquipmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapMachineryAndEquipmentMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaapFurnitureAndFixturesMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaapFurnitureAndFixturesMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaapPropertyPlantAndEquipmentUsefulLife_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaapPropertyPlantAndEquipmentUsefulLife_50" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfAnti-dilutiveSecuritiesExcludedFromComputationOfEarningsDetails" xlink:title="999036 - Disclosure - SCHEDULE OF ANTI-DILUTIVE SECURITIES EXCLUDED FROM COMPUTATION OF EARNINGS (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_us-gaapWarrantMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesAWarrantsMember" xlink:label="loc_PPCBSeriesAWarrantsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_PPCBSeriesAWarrantsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCWarrantsMember" xlink:label="loc_PPCBSeriesCWarrantsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_PPCBSeriesCWarrantsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCWarrantOneMember" xlink:label="loc_PPCBSeriesCWarrantOneMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_PPCBSeriesCWarrantOneMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCConvertiblePreferredStockMember" xlink:label="loc_PPCBSeriesCConvertiblePreferredStockMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_PPCBSeriesCConvertiblePreferredStockMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtSecuritiesMember" xlink:label="loc_us-gaapConvertibleDebtSecuritiesMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_us-gaapConvertibleDebtSecuritiesMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_250" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/GoingConcernDetailsNarrative" xlink:title="999037 - Disclosure - GOING CONCERN (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SubstantialDoubtAboutGoingConcernLineItems" xlink:label="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SubstantialDoubtAboutGoingConcernTable" xlink:label="loc_PPCBSubstantialDoubtAboutGoingConcernTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_PPCBSubstantialDoubtAboutGoingConcernTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="loc_us-gaapSeriesCPreferredStockMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesCPreferredStockMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapNetIncomeLoss_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInOperatingActivities_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapNetCashProvidedByUsedInOperatingActivities_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_WorkingCapitalDeficit" xlink:label="loc_PPCBWorkingCapitalDeficit_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_PPCBWorkingCapitalDeficit_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_90" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfCommonStock_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfCommonStock_90" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_90" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_90" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_90" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfWarrants" xlink:label="loc_us-gaapPaymentsForRepurchaseOfWarrants_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBSubstantialDoubtAboutGoingConcernLineItems" xlink:to="loc_us-gaapPaymentsForRepurchaseOfWarrants_90" xlink:type="arc" order="8" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfPropertyPlantAndEquipmentDetails" xlink:title="999038 - Disclosure - SCHEDULE OF PROPERTY PLANT AND EQUIPMENT (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/PropertyAndEquipmentDetailsNarrative" xlink:title="999039 - Disclosure - PROPERTY AND EQUIPMENT (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/DueToAndLoansFromFormerDirector-RelatedPartyDetailsNarrative" xlink:title="999040 - Disclosure - DUE TO AND LOANS FROM FORMER DIRECTOR - RELATED PARTY (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorMember" xlink:label="loc_PPCBFormerDirectorMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorsMember" xlink:label="loc_PPCBFormerDirectorsMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorsMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtExchangeMember" xlink:label="loc_PPCBDebtExchangeMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBDebtExchangeMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaapOtherLiabilitiesCurrent_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapOtherLiabilitiesCurrent_100" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherReceivablesNetCurrent" xlink:label="loc_us-gaapOtherReceivablesNetCurrent_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapOtherReceivablesNetCurrent_100" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SettlementOfLoansForSharesOfCommonStock" xlink:label="loc_PPCBSettlementOfLoansForSharesOfCommonStock_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBSettlementOfLoansForSharesOfCommonStock_100" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_100" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_100" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_us-gaapDebtInstrumentFairValue_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapDebtInstrumentFairValue_100" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtFairValueDisclosures" xlink:label="loc_us-gaapConvertibleDebtFairValueDisclosures_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapConvertibleDebtFairValueDisclosures_100" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableCurrent" xlink:label="loc_us-gaapLoansPayableCurrent_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapLoansPayableCurrent_100" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_100" xlink:type="arc" order="9" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/LoansDetailsNarrative" xlink:title="999041 - Disclosure - LOANS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaapLineOfCreditFacilityLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaapLineOfCreditFacilityTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapLineOfCreditFacilityTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapInvestorMember_90" xlink:type="arc" order="91" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember" xlink:label="loc_srtDirectorMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_srtDirectorMember_150" xlink:type="arc" order="151" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TwoInvestorsMember" xlink:label="loc_PPCBTwoInvestorsMember_490" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBTwoInvestorsMember_490" xlink:type="arc" order="492" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LoanAgreementMember" xlink:label="loc_PPCBLoanAgreementMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBLoanAgreementMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LetterAgreementMember" xlink:label="loc_PPCBLetterAgreementMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBLetterAgreementMember_250" xlink:type="arc" order="251" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementMember_420" xlink:type="arc" order="421" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ExchangeAgreementMember" xlink:label="loc_PPCBExchangeAgreementMember_450" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBExchangeAgreementMember_450" xlink:type="arc" order="452" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtExchangeAgreementMember" xlink:label="loc_PPCBDebtExchangeAgreementMember_490" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBDebtExchangeAgreementMember_490" xlink:type="arc" order="491" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember" xlink:label="loc_srtDirectorMember_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtDirectorMember_230" xlink:type="arc" order="231" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapWarrantMember_270" xlink:type="arc" order="271" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="loc_us-gaapMeasurementInputTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_us-gaapMeasurementInputTypeAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedTermMember" xlink:label="loc_us-gaapMeasurementInputExpectedTermMember_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedTermMember_290" xlink:type="arc" order="291" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:label="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_300" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_300" xlink:type="arc" order="301" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="loc_us-gaapMeasurementInputPriceVolatilityMember_310" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputPriceVolatilityMember_310" xlink:type="arc" order="311" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CoventryEnterprisesLLCSecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBCoventryEnterprisesLLCSecuritiesPurchaseAgreementMember_320" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBCoventryEnterprisesLLCSecuritiesPurchaseAgreementMember_320" xlink:type="arc" order="322" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CrownBridgePartnersLLCMember" xlink:label="loc_PPCBCrownBridgePartnersLLCMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBCrownBridgePartnersLLCMember_420" xlink:type="arc" order="422" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLineOfCreditFacilityTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_570" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_570" xlink:type="arc" order="571" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableCurrent" xlink:label="loc_us-gaapLoansPayableCurrent_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapLoansPayableCurrent_680" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_680" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfBankDebt" xlink:label="loc_us-gaapRepaymentsOfBankDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapRepaymentsOfBankDebt_680" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaapInterestExpenseDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapInterestExpenseDebt_680" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_680" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_680" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_680" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger" xlink:label="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_680" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfRelatedPartyDebt" xlink:label="loc_us-gaapRepaymentsOfRelatedPartyDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapRepaymentsOfRelatedPartyDebt_680" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayable" xlink:label="loc_us-gaapLoansPayable_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapLoansPayable_680" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaapInterestExpense_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapInterestExpense_680" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaapDebtInstrumentTerm_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentTerm_680" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_680" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_680" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaapFairValueAdjustmentOfWarrants_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapFairValueAdjustmentOfWarrants_680" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaapSaleOfStockPricePerShare_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapSaleOfStockPricePerShare_680" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantExercisePriceIncrease" xlink:label="loc_us-gaapWarrantExercisePriceIncrease_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapWarrantExercisePriceIncrease_680" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMeasurementInput" xlink:label="loc_us-gaapDebtInstrumentMeasurementInput_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentMeasurementInput_680" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfConvertibleDebt" xlink:label="loc_us-gaapRepaymentsOfConvertibleDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapRepaymentsOfConvertibleDebt_680" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="loc_us-gaapAmortizationOfDebtDiscountPremium_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapAmortizationOfDebtDiscountPremium_680" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_680" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscount_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscount_680" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermLoansPayable" xlink:label="loc_us-gaapLongTermLoansPayable_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapLongTermLoansPayable_680" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscountPremiumNet_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscountPremiumNet_680" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InterestPayable" xlink:label="loc_PPCBInterestPayable_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_PPCBInterestPayable_680" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebt" xlink:label="loc_us-gaapConvertibleDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapConvertibleDebt_680" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="loc_us-gaapInterestPayableCurrentAndNoncurrent_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapInterestPayableCurrentAndNoncurrent_680" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_680" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_680" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_680" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:label="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_680" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_us-gaapDebtInstrumentFairValue_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentFairValue_680" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtFairValueDisclosures" xlink:label="loc_us-gaapConvertibleDebtFairValueDisclosures_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapConvertibleDebtFairValueDisclosures_680" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapNotesPayable_680" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDateDescription" xlink:label="loc_us-gaapDebtInstrumentMaturityDateDescription_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDateDescription_680" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InterestLoanPayable" xlink:label="loc_PPCBInterestLoanPayable_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_PPCBInterestLoanPayable_680" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFeeAmount" xlink:label="loc_us-gaapDebtInstrumentFeeAmount_680" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLineOfCreditFacilityLineItems" xlink:to="loc_us-gaapDebtInstrumentFeeAmount_680" xlink:type="arc" order="36" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfPromissoryNotesOutstandingDetails" xlink:title="999042 - Disclosure - SCHEDULE OF PROMISSORY NOTES OUTSTANDING (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtLineItems" xlink:label="loc_us-gaapShortTermDebtLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShortTermDebtTable" xlink:label="loc_us-gaapScheduleOfShortTermDebtTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapScheduleOfShortTermDebtTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShortTermDebtTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PromissoryNoteMember" xlink:label="loc_PPCBPromissoryNoteMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBPromissoryNoteMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapNotesPayable_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscount_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscount_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_40" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/NotesPayableAndConvertibleNotesDetailsNarrative" xlink:title="999043 - Disclosure - NOTES PAYABLE AND CONVERTIBLE NOTES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NotesPayableAndConvertibleNotesLineItems" xlink:label="loc_PPCBNotesPayableAndConvertibleNotesLineItems" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NotesPayableAndConvertibleNotesTable" xlink:label="loc_PPCBNotesPayableAndConvertibleNotesTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaapShortTermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_us-gaapShortTermDebtTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableMember" xlink:label="loc_us-gaapLoansPayableMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_us-gaapLoansPayableMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RedRoadHoldingsPromissoryNoteMember" xlink:label="loc_PPCBRedRoadHoldingsPromissoryNoteMember_620" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_PPCBRedRoadHoldingsPromissoryNoteMember_620" xlink:type="arc" order="621" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ThreeOutstandingConvertibleNotesMember" xlink:label="loc_PPCBThreeOutstandingConvertibleNotesMember_2440" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_PPCBThreeOutstandingConvertibleNotesMember_2440" xlink:type="arc" order="2441" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MaturityExtensionAgreementMember" xlink:label="loc_PPCBMaturityExtensionAgreementMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBMaturityExtensionAgreementMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementMember_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementMember_290" xlink:type="arc" order="291" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementOneMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementOneMember_390" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementOneMember_390" xlink:type="arc" order="391" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AugustTenTwoThousandAndSeventeenConsultingAgreementMember" xlink:label="loc_PPCBAugustTenTwoThousandAndSeventeenConsultingAgreementMember_1150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBAugustTenTwoThousandAndSeventeenConsultingAgreementMember_1150" xlink:type="arc" order="1151" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_us-gaapInvestorMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaapLongtermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_us-gaapLongtermDebtTypeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaapLongtermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapLongtermDebtTypeAxis" xlink:to="loc_us-gaapLongtermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaapLongtermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLongtermDebtTypeAxis" xlink:to="loc_us-gaapLongtermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PromissoryNoteMember" xlink:label="loc_PPCBPromissoryNoteMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLongtermDebtTypeDomain" xlink:to="loc_PPCBPromissoryNoteMember_130" xlink:type="arc" order="132" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ThousandEightHundredDiagonalLendingLLCMember" xlink:label="loc_PPCBThousandEightHundredDiagonalLendingLLCMember_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBThousandEightHundredDiagonalLendingLLCMember_190" xlink:type="arc" order="191" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OneFortyFourCapitalMember" xlink:label="loc_PPCBOneFortyFourCapitalMember_830" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBOneFortyFourCapitalMember_830" xlink:type="arc" order="832" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_GSCapitalPartnersLLCMember" xlink:label="loc_PPCBGSCapitalPartnersLLCMember_940" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBGSCapitalPartnersLLCMember_940" xlink:type="arc" order="942" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_HundredAndFourLLCMember" xlink:label="loc_PPCBHundredAndFourLLCMember_1220" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBHundredAndFourLLCMember_1220" xlink:type="arc" order="1222" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_GeebisConsultingLLCMember" xlink:label="loc_PPCBGeebisConsultingLLCMember_1360" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBGeebisConsultingLLCMember_1360" xlink:type="arc" order="1362" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CoventryEnterprisesLLCSecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBCoventryEnterprisesLLCSecuritiesPurchaseAgreementMember_2260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBCoventryEnterprisesLLCSecuritiesPurchaseAgreementMember_2260" xlink:type="arc" order="2262" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CrownBridgePartnersLLCMember" xlink:label="loc_PPCBCrownBridgePartnersLLCMember_2290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBCrownBridgePartnersLLCMember_2290" xlink:type="arc" order="2292" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_550" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_550" xlink:type="arc" order="552" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PromissoryNoteMember" xlink:label="loc_PPCBPromissoryNoteMember_730" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBPromissoryNoteMember_730" xlink:type="arc" order="732" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConvertibleNotesOneMember" xlink:label="loc_PPCBConvertibleNotesOneMember_1530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBConvertibleNotesOneMember_1530" xlink:type="arc" order="1531" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_JulyElevenTwentyTwentyTwoThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBJulyElevenTwentyTwentyTwoThousandEighthundredDiagonalNoteMember_1870" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBJulyElevenTwentyTwentyTwoThousandEighthundredDiagonalNoteMember_1870" xlink:type="arc" order="1873" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_JulySixTwentyTwentyThreeThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBJulySixTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1890" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBJulySixTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1890" xlink:type="arc" order="1893" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_JulyNineteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBJulyNineteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1910" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBJulyNineteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1910" xlink:type="arc" order="1913" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AugustSixteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBAugustSixteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1930" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBAugustSixteenTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1930" xlink:type="arc" order="1933" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OctoberTwentyTwentyTwentyThreeThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBOctoberTwentyTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1950" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBOctoberTwentyTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1950" xlink:type="arc" order="1953" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NovemberTwentyNineTwentyTwentyThreeThousandEighthundredDiagonalNoteMember" xlink:label="loc_PPCBNovemberTwentyNineTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1970" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBNovemberTwentyNineTwentyTwentyThreeThousandEighthundredDiagonalNoteMember_1970" xlink:type="arc" order="1973" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_760" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_760" xlink:type="arc" order="763" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_770" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_770" xlink:type="arc" order="773" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis" xlink:label="loc_srtStatementScenarioAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesTable" xlink:to="loc_srtStatementScenarioAxis" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="loc_srtScenarioUnspecifiedDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtStatementScenarioAxis" xlink:to="loc_srtScenarioUnspecifiedDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="loc_srtScenarioUnspecifiedDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtStatementScenarioAxis" xlink:to="loc_srtScenarioUnspecifiedDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioForecastMember" xlink:label="loc_srtScenarioForecastMember_1660" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtScenarioUnspecifiedDomain" xlink:to="loc_srtScenarioForecastMember_1660" xlink:type="arc" order="1663" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_2520" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountCurrent" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscountCurrent_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscountCurrent_2520" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_2520" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_2520" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentDescription" xlink:label="loc_us-gaapDebtInstrumentDescription_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentDescription_2520" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_2520" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtAverageAmountOutstanding" xlink:label="loc_us-gaapLongTermDebtAverageAmountOutstanding_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapLongTermDebtAverageAmountOutstanding_2520" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="loc_us-gaapInterestPayableCurrentAndNoncurrent_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapInterestPayableCurrentAndNoncurrent_2520" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAnnualPrincipalPayment" xlink:label="loc_us-gaapDebtInstrumentAnnualPrincipalPayment_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentAnnualPrincipalPayment_2520" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepurchaseAmount" xlink:label="loc_us-gaapDebtInstrumentRepurchaseAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentRepurchaseAmount_2520" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentDebtDefaultInterestRate" xlink:label="loc_PPCBDebtInstrumentDebtDefaultInterestRate_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentDebtDefaultInterestRate_2520" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPaymentTerms" xlink:label="loc_us-gaapDebtInstrumentPaymentTerms_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentPaymentTerms_2520" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepaidPrincipal" xlink:label="loc_us-gaapDebtInstrumentRepaidPrincipal_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentRepaidPrincipal_2520" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtDefaultLongtermDebtAmount" xlink:label="loc_us-gaapDebtDefaultLongtermDebtAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtDefaultLongtermDebtAmount_2520" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaapDebtInstrumentCarryingAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentCarryingAmount_2520" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaapDebtInstrumentUnamortizedDiscount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedDiscount_2520" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="loc_us-gaapAmortizationOfDebtDiscountPremium_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapAmortizationOfDebtDiscountPremium_2520" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaapPaymentsOfFinancingCosts_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapPaymentsOfFinancingCosts_2520" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfDebt" xlink:label="loc_us-gaapProceedsFromIssuanceOfDebt_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfDebt_2520" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_2520" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPeriodicPayment" xlink:label="loc_us-gaapDebtInstrumentPeriodicPayment_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentPeriodicPayment_2520" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:label="loc_us-gaapDebtInstrumentPeriodicPaymentInterest_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentPeriodicPaymentInterest_2520" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfShortTermDebt" xlink:label="loc_us-gaapRepaymentsOfShortTermDebt_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapRepaymentsOfShortTermDebt_2520" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentDebtConversionRate" xlink:label="loc_PPCBDebtInstrumentDebtConversionRate_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentDebtConversionRate_2520" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_BeneficialOwnershipLimitationPercentage" xlink:label="loc_PPCBBeneficialOwnershipLimitationPercentage_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBBeneficialOwnershipLimitationPercentage_2520" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentDiscountRate" xlink:label="loc_PPCBDebtInstrumentDiscountRate_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentDiscountRate_2520" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaapNotesPayable_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapNotesPayable_2520" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaapDeferredFinanceCostsNet_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDeferredFinanceCostsNet_2520" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionRatio1_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionRatio1_2520" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfOutstandingSharesOfCommonStock" xlink:label="loc_PPCBPercentageOfOutstandingSharesOfCommonStock_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBPercentageOfOutstandingSharesOfCommonStock_2520" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentSettlementDebtAmount" xlink:label="loc_PPCBDebtInstrumentSettlementDebtAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentSettlementDebtAmount_2520" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PenaltyAmount" xlink:label="loc_PPCBPenaltyAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBPenaltyAmount_2520" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:label="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentIncreaseAccruedInterest_2520" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedPremium" xlink:label="loc_us-gaapDebtInstrumentUnamortizedPremium_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentUnamortizedPremium_2520" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaapLegalFees_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapLegalFees_2520" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentIncreasePrincipalPercentage" xlink:label="loc_PPCBDebtInstrumentIncreasePrincipalPercentage_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentIncreasePrincipalPercentage_2520" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_2520" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionDescription" xlink:label="loc_us-gaapDebtConversionDescription_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtConversionDescription_2520" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaapDerivativeLiabilities_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDerivativeLiabilities_2520" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFeeAmount" xlink:label="loc_us-gaapDebtInstrumentFeeAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentFeeAmount_2520" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InterestPayable" xlink:label="loc_PPCBInterestPayable_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBInterestPayable_2520" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtDefaultAmountPercentage" xlink:label="loc_PPCBDebtDefaultAmountPercentage_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtDefaultAmountPercentage_2520" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockAmountConverted1" xlink:label="loc_us-gaapConversionOfStockAmountConverted1_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapConversionOfStockAmountConverted1_2520" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:label="loc_us-gaapAccretionAmortizationOfDiscountsAndPremiumsInvestments_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapAccretionAmortizationOfDiscountsAndPremiumsInvestments_2520" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease" xlink:label="loc_us-gaapDebtInstrumentInterestRateIncreaseDecrease_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateIncreaseDecrease_2520" xlink:type="arc" order="44" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger" xlink:label="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_2520" xlink:type="arc" order="45" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtDefaultShorttermDebtAmount" xlink:label="loc_us-gaapDebtDefaultShorttermDebtAmount_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapDebtDefaultShorttermDebtAmount_2520" xlink:type="arc" order="46" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromConvertibleDebt" xlink:label="loc_us-gaapProceedsFromConvertibleDebt_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapProceedsFromConvertibleDebt_2520" xlink:type="arc" order="47" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentGuaranteedInterest" xlink:label="loc_PPCBDebtInstrumentGuaranteedInterest_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_PPCBDebtInstrumentGuaranteedInterest_2520" xlink:type="arc" order="48" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaapSharesIssued_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapSharesIssued_2520" xlink:type="arc" order="49" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_2520" xlink:type="arc" order="50" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfConvertibleDebt" xlink:label="loc_us-gaapRepaymentsOfConvertibleDebt_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapRepaymentsOfConvertibleDebt_2520" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleNotesPayableCurrent" xlink:label="loc_us-gaapConvertibleNotesPayableCurrent_2520" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_PPCBNotesPayableAndConvertibleNotesLineItems" xlink:to="loc_us-gaapConvertibleNotesPayableCurrent_2520" xlink:type="arc" order="52" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfConvertibleNotesDetails" xlink:title="999044 - Disclosure - SCHEDULE OF CONVERTIBLE NOTES (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfKeyInputsWarrantLiabilityDetails" xlink:title="999045 - Disclosure - SCHEDULE OF KEY INPUTS WARRANT LIABILITY (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaapBusinessAcquisitionLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaapScheduleOfBusinessAcquisitionsByAcquisitionTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="loc_us-gaapMeasurementInputTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="loc_us-gaapMeasurementInputTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedTermMember" xlink:label="loc_us-gaapMeasurementInputExpectedTermMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedTermMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="loc_us-gaapMeasurementInputPriceVolatilityMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputPriceVolatilityMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:label="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputSharePriceMember" xlink:label="loc_us-gaapMeasurementInputSharePriceMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputSharePriceMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedDividendRateMember" xlink:label="loc_us-gaapMeasurementInputExpectedDividendRateMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedDividendRateMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExercisePriceMember" xlink:label="loc_us-gaapMeasurementInputExercisePriceMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExercisePriceMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingMeasurementInput" xlink:label="loc_us-gaapWarrantsAndRightsOutstandingMeasurementInput_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapWarrantsAndRightsOutstandingMeasurementInput_130" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SeriesCPreferredStockAndSeriesCWarrantsDetailsNarrative" xlink:title="999046 - Disclosure - SERIES C PREFERRED STOCK AND SERIES C WARRANTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaapPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapPreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="loc_us-gaapSeriesCPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesCPreferredStockMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCWarrantsMember" xlink:label="loc_PPCBSeriesCWarrantsMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesCWarrantsMember_120" xlink:type="arc" order="122" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_HexstoneCapitalLLCMember" xlink:label="loc_PPCBHexstoneCapitalLLCMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBHexstoneCapitalLLCMember_0" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_HexstoneCapitalLLCMember" xlink:label="loc_PPCBHexstoneCapitalLLCMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBHexstoneCapitalLLCMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_us-gaapInvestorMember_120" xlink:type="arc" order="123" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_230" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_230" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockStatedValuePerShare" xlink:label="loc_PPCBPreferredStockStatedValuePerShare_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockStatedValuePerShare_230" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_230" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaapLegalFees_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapLegalFees_230" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_230" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_230" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockLiquidationPreference" xlink:label="loc_us-gaapPreferredStockLiquidationPreference_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockLiquidationPreference_230" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockStatedValuePercentage" xlink:label="loc_PPCBPreferredStockStatedValuePercentage_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockStatedValuePercentage_230" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockDividendRatePercentage" xlink:label="loc_us-gaapPreferredStockDividendRatePercentage_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockDividendRatePercentage_230" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DividendRateAnnualIncreasePercentage" xlink:label="loc_PPCBDividendRateAnnualIncreasePercentage_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBDividendRateAnnualIncreasePercentage_230" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockConversionPrice" xlink:label="loc_PPCBPreferredStockConversionPrice_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockConversionPrice_230" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockConvertibleConversionPrice" xlink:label="loc_us-gaapPreferredStockConvertibleConversionPrice_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockConvertibleConversionPrice_230" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockConversionBasis" xlink:label="loc_us-gaapPreferredStockConversionBasis_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockConversionBasis_230" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockConversionBasisForBankruptcy" xlink:label="loc_PPCBPreferredStockConversionBasisForBankruptcy_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockConversionBasisForBankruptcy_230" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockFairValueAmount" xlink:label="loc_PPCBPreferredStockFairValueAmount_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockFairValueAmount_230" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PreferredStockDeemedDividendAmount" xlink:label="loc_PPCBPreferredStockDeemedDividendAmount_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBPreferredStockDeemedDividendAmount_230" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredOfferingCosts" xlink:label="loc_us-gaapDeferredOfferingCosts_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapDeferredOfferingCosts_230" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RegistrationRightsPenaltyAmount" xlink:label="loc_PPCBRegistrationRightsPenaltyAmount_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBRegistrationRightsPenaltyAmount_230" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_230" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaapConversionOfStockSharesConverted1_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapConversionOfStockSharesConverted1_230" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_230" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="loc_us-gaapProceedsFromWarrantExercises_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapProceedsFromWarrantExercises_230" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FairValueOfWarrantsLiability" xlink:label="loc_PPCBFairValueOfWarrantsLiability_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBFairValueOfWarrantsLiability_230" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaapPreferredStockSharesOutstanding_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockSharesOutstanding_230" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockRedemptionAmount" xlink:label="loc_us-gaapPreferredStockRedemptionAmount_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapPreferredStockRedemptionAmount_230" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InitialFairValueOfWarrantLiabilityUponIssuance" xlink:label="loc_PPCBInitialFairValueOfWarrantLiabilityUponIssuance_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBInitialFairValueOfWarrantLiabilityUponIssuance_230" xlink:type="arc" order="26" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfIncomeTaxProvisionDetails" xlink:title="999047 - Disclosure - SCHEDULE OF INCOME TAX PROVISION (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srtStatementGeographicalAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapEffectiveIncomeTaxRateReconciliationTable" xlink:to="loc_srtStatementGeographicalAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US" xlink:label="loc_countryUS_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_countryUS_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:label="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_30" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaapIncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_30" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_30" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaapIncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_30" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_30" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:label="loc_us-gaapIncomeTaxReconciliationForeignIncomeTaxRateDifferential_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxReconciliationForeignIncomeTaxRateDifferential_30" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_30" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationPriorYearIncomeTaxes" xlink:label="loc_us-gaapIncomeTaxReconciliationPriorYearIncomeTaxes_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxReconciliationPriorYearIncomeTaxes_30" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes_30" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:label="loc_us-gaapIncomeTaxReconciliationOtherAdjustments_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxReconciliationOtherAdjustments_30" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:label="loc_us-gaapEffectiveIncomeTaxRateReconciliationOtherAdjustments_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateReconciliationOtherAdjustments_30" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaapIncomeTaxExpenseBenefit_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxExpenseBenefit_30" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaapEffectiveIncomeTaxRateContinuingOperations_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEffectiveIncomeTaxRateContinuingOperations_30" xlink:type="arc" order="12" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:title="999048 - Disclosure - SCHEDULE OF DEFERRED TAX ASSETS AND LIABILITIES (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/IncomeTaxesDetailsNarrative" xlink:title="999049 - Disclosure - INCOME TAXES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CaresActMember" xlink:label="loc_PPCBCaresActMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBCaresActMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srtStatementGeographicalAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_srtStatementGeographicalAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US" xlink:label="loc_countryUS_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_countryUS_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_AU" xlink:label="loc_countryAU_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_countryAU_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaapIncomeTaxExpenseBenefit_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapIncomeTaxExpenseBenefit_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExaminationDescription" xlink:label="loc_us-gaapIncomeTaxExaminationDescription_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapIncomeTaxExaminationDescription_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaapOperatingLossCarryforwards_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapOperatingLossCarryforwards_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaapUnrecognizedTaxBenefits_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapUnrecognizedTaxBenefits_90" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnrecognizedTaxBenefitPeriodIncreaseDecrease" xlink:label="loc_PPCBUnrecognizedTaxBenefitPeriodIncreaseDecrease_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_PPCBUnrecognizedTaxBenefitPeriodIncreaseDecrease_90" xlink:type="arc" order="4" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SummaryOfWarrantActivityDetails" xlink:title="999050 - Disclosure - SUMMARY OF WARRANT ACTIVITY (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaapPreferredStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapPreferredStockMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="loc_us-gaapSeriesCPreferredStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesCPreferredStockMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageOutstanding" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageOutstanding_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageOutstanding_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceIssued" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceIssued_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceIssued_90" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_90" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExercised" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExercised_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExercised_90" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_90" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceForfeited" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceForfeited_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceForfeited_90" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations_90" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExpired" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExpired_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAveragePriceExpired_90" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber_90" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageExercisable" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageExercisable_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageExercisable_90" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageRemainingContractualTerms" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageRemainingContractualTerms_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageRemainingContractualTerms_90" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentsAggregateIntrinsicValueOutstanding" xlink:label="loc_PPCBSharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentsAggregateIntrinsicValueOutstanding_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBSharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentsAggregateIntrinsicValueOutstanding_90" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentWeightedAverageOutstanding" xlink:label="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentWeightedAverageOutstanding_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_PPCBShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentWeightedAverageOutstanding_90" xlink:type="arc" order="16" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfShareBasedCompensationStockOptionsActivityDetails" xlink:title="999051 - Disclosure - SCHEDULE OF SHARE BASED COMPENSATION STOCK OPTIONS ACTIVITY (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/StockholdersEquityDeficitDetailsNarrative" xlink:title="999052 - Disclosure - STOCKHOLDERS&#8217; EQUITY (DEFICIT) (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaapClassOfStockLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaapScheduleOfStockByClassTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapScheduleOfStockByClassTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaapSeriesAPreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesAPreferredStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesBPreferredStockMember" xlink:label="loc_us-gaapSeriesBPreferredStockMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesBPreferredStockMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="loc_us-gaapSeriesCPreferredStockMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesCPreferredStockMember_200" xlink:type="arc" order="202" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesAWarrantsMember" xlink:label="loc_PPCBSeriesAWarrantsMember_1270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesAWarrantsMember_1270" xlink:type="arc" order="1272" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesBWarrantsMember" xlink:label="loc_PPCBSeriesBWarrantsMember_1290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesBWarrantsMember_1290" xlink:type="arc" order="1292" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCWarrantsMember" xlink:label="loc_PPCBSeriesCWarrantsMember_1310" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesCWarrantsMember_1310" xlink:type="arc" order="1312" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnderwritingAgreementMember" xlink:label="loc_PPCBUnderwritingAgreementMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBUnderwritingAgreementMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnderlyingFinancingAgreementsMember" xlink:label="loc_PPCBUnderlyingFinancingAgreementsMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBUnderlyingFinancingAgreementsMember_180" xlink:type="arc" order="181" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ThreeMonthConsultingAgreementMember" xlink:label="loc_PPCBThreeMonthConsultingAgreementMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBThreeMonthConsultingAgreementMember_250" xlink:type="arc" order="251" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingAgreementMember" xlink:label="loc_PPCBConsultingAgreementMember_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBConsultingAgreementMember_260" xlink:type="arc" order="261" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SixMonthsConsultingAgreementMember" xlink:label="loc_PPCBSixMonthsConsultingAgreementMember_300" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSixMonthsConsultingAgreementMember_300" xlink:type="arc" order="301" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingAgreementTwoMember" xlink:label="loc_PPCBConsultingAgreementTwoMember_430" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBConsultingAgreementTwoMember_430" xlink:type="arc" order="431" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_HexstoneCapitalLLCMember" xlink:label="loc_PPCBHexstoneCapitalLLCMember_630" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBHexstoneCapitalLLCMember_630" xlink:type="arc" order="633" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CommonStockPurchaseAgreementMember" xlink:label="loc_PPCBCommonStockPurchaseAgreementMember_730" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBCommonStockPurchaseAgreementMember_730" xlink:type="arc" order="731" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtExchangeMember" xlink:label="loc_PPCBDebtExchangeMember_1120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBDebtExchangeMember_1120" xlink:type="arc" order="1121" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtExchangeAgreementMember" xlink:label="loc_PPCBDebtExchangeAgreementMember_1160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBDebtExchangeAgreementMember_1160" xlink:type="arc" order="1161" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementMember_1250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementMember_1250" xlink:type="arc" order="1251" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LetterAgreementMember" xlink:label="loc_PPCBLetterAgreementMember_1350" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBLetterAgreementMember_1350" xlink:type="arc" order="1351" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_60" xlink:type="arc" order="62" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RepresentativesWarrantsMember" xlink:label="loc_PPCBRepresentativesWarrantsMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_PPCBRepresentativesWarrantsMember_80" xlink:type="arc" order="82" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaapPreferredStockMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapPreferredStockMember_200" xlink:type="arc" order="201" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesBWarrantsMember" xlink:label="loc_PPCBSeriesBWarrantsMember_1320" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_PPCBSeriesBWarrantsMember_1320" xlink:type="arc" order="1321" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_1340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapWarrantMember_1340" xlink:type="arc" order="1341" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaapSubsidiarySaleOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaapSaleOfStockNameOfTransactionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:to="loc_us-gaapSaleOfStockNameOfTransactionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaapSaleOfStockNameOfTransactionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:to="loc_us-gaapSaleOfStockNameOfTransactionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IPOMember" xlink:label="loc_us-gaapIPOMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSaleOfStockNameOfTransactionDomain" xlink:to="loc_us-gaapIPOMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaapShortTermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapShortTermDebtTypeAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaapConvertibleDebtMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_us-gaapConvertibleDebtMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingInvestorRelationsAndBusinessAdvisoryServicesMember" xlink:label="loc_PPCBConsultingInvestorRelationsAndBusinessAdvisoryServicesMember_450" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_PPCBConsultingInvestorRelationsAndBusinessAdvisoryServicesMember_450" xlink:type="arc" order="452" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingInvestorRelationsAndBusinessAdvisoryServicesOneMember" xlink:label="loc_PPCBConsultingInvestorRelationsAndBusinessAdvisoryServicesOneMember_480" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_PPCBConsultingInvestorRelationsAndBusinessAdvisoryServicesOneMember_480" xlink:type="arc" order="481" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OfficersEmployeesDirectorsAndConsultantsMember" xlink:label="loc_PPCBOfficersEmployeesDirectorsAndConsultantsMember_980" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_PPCBOfficersEmployeesDirectorsAndConsultantsMember_980" xlink:type="arc" order="982" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_1270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_us-gaapInvestorMember_1270" xlink:type="arc" order="1273" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_500" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_500" xlink:type="arc" order="503" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_510" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_510" xlink:type="arc" order="513" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaapRestrictedStockUnitsRSUMember_600" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapRestrictedStockUnitsRSUMember_600" xlink:type="arc" order="601" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TwoThousandNinteenEquityIncentivePlanMember" xlink:label="loc_PPCBTwoThousandNinteenEquityIncentivePlanMember_640" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_PPCBTwoThousandNinteenEquityIncentivePlanMember_640" xlink:type="arc" order="641" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_730" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapInvestorMember_730" xlink:type="arc" order="733" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorMember" xlink:label="loc_PPCBFormerDirectorMember_1130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorMember_1130" xlink:type="arc" order="1131" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TwoInvestorsMember" xlink:label="loc_PPCBTwoInvestorsMember_1160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBTwoInvestorsMember_1160" xlink:type="arc" order="1162" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AffiliatedEntityMember" xlink:label="loc_srtAffiliatedEntityMember_1370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_srtAffiliatedEntityMember_1370" xlink:type="arc" order="1372" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DutchessMember" xlink:label="loc_PPCBDutchessMember_800" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBDutchessMember_800" xlink:type="arc" order="802" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AuctusFundLLCMember" xlink:label="loc_PPCBAuctusFundLLCMember_1380" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBAuctusFundLLCMember_1380" xlink:type="arc" order="1382" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaapClassOfWarrantOrRightAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapClassOfWarrantOrRightAxis" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesAWarrantsMember" xlink:label="loc_PPCBSeriesAWarrantsMember_840" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_PPCBSeriesAWarrantsMember_840" xlink:type="arc" order="841" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesAWarrantMember" xlink:label="loc_PPCBSeriesAWarrantMember_860" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_PPCBSeriesAWarrantMember_860" xlink:type="arc" order="861" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PrefundedWarrantsMember" xlink:label="loc_PPCBPrefundedWarrantsMember_1260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_PPCBPrefundedWarrantsMember_1260" xlink:type="arc" order="1262" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesBWarrantsMember" xlink:label="loc_PPCBSeriesBWarrantsMember_1330" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_PPCBSeriesBWarrantsMember_1330" xlink:type="arc" order="1331" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AugustTwoThousandNineteenAuctusNoteMember" xlink:label="loc_PPCBAugustTwoThousandNineteenAuctusNoteMember_1380" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBAugustTwoThousandNineteenAuctusNoteMember_1380" xlink:type="arc" order="1383" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="loc_us-gaapMeasurementInputTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapMeasurementInputTypeAxis" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedDividendRateMember" xlink:label="loc_us-gaapMeasurementInputExpectedDividendRateMember_1410" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedDividendRateMember_1410" xlink:type="arc" order="1411" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedTermMember" xlink:label="loc_us-gaapMeasurementInputExpectedTermMember_1420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedTermMember_1420" xlink:type="arc" order="1421" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:label="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_1430" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_1430" xlink:type="arc" order="1431" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="loc_us-gaapMeasurementInputPriceVolatilityMember_1440" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputPriceVolatilityMember_1440" xlink:type="arc" order="1441" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaapPreferredStockSharesAuthorized_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesAuthorized_1460" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_1460" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_1460" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaapPreferredStockSharesOutstanding_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesOutstanding_1460" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaapSharesIssued_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharesIssued_1460" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_1460" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaapSaleOfStockPricePerShare_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSaleOfStockPricePerShare_1460" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_1460" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfInitialPublicOffering" xlink:label="loc_us-gaapPaymentsForRepurchaseOfInitialPublicOffering_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPaymentsForRepurchaseOfInitialPublicOffering_1460" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfCommonStock_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfCommonStock_1460" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NetProceedsFromIssuanceOfCommonStock" xlink:label="loc_PPCBNetProceedsFromIssuanceOfCommonStock_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBNetProceedsFromIssuanceOfCommonStock_1460" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredOfferingCosts" xlink:label="loc_us-gaapDeferredOfferingCosts_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDeferredOfferingCosts_1460" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_1460" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_1460" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="loc_us-gaapInterestPayableCurrentAndNoncurrent_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapInterestPayableCurrentAndNoncurrent_1460" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFeeAmount" xlink:label="loc_us-gaapDebtInstrumentFeeAmount_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentFeeAmount_1460" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_us-gaapDebtInstrumentFairValue_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentFairValue_1460" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtFairValueDisclosures" xlink:label="loc_us-gaapConvertibleDebtFairValueDisclosures_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapConvertibleDebtFairValueDisclosures_1460" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaapDerivativeFairValueOfDerivativeNet_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDerivativeFairValueOfDerivativeNet_1460" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ExtinguishmentOfDebtGainLossNetOfTax" xlink:label="loc_us-gaapExtinguishmentOfDebtGainLossNetOfTax_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapExtinguishmentOfDebtGainLossNetOfTax_1460" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital" xlink:label="loc_PPCBReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital_1460" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaapCommonStockCapitalSharesReservedForFutureIssuance_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockCapitalSharesReservedForFutureIssuance_1460" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_1460" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaapConversionOfStockSharesConverted1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapConversionOfStockSharesConverted1_1460" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockValue_1460" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_1460" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MonthlyFeeForServices" xlink:label="loc_PPCBMonthlyFeeForServices_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBMonthlyFeeForServices_1460" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForFees" xlink:label="loc_us-gaapPaymentsForFees_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPaymentsForFees_1460" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueConversionOfConvertibleSecurities_1460" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_1460" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_1460" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_1460" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_1460" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssuedPricePerShare" xlink:label="loc_us-gaapSharesIssuedPricePerShare_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharesIssuedPricePerShare_1460" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPrepaidExpenseCurrent_1460" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseNoncurrent" xlink:label="loc_us-gaapPrepaidExpenseNoncurrent_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPrepaidExpenseNoncurrent_1460" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PrepaidStockBasedExpenseCurrent" xlink:label="loc_PPCBPrepaidStockBasedExpenseCurrent_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBPrepaidStockBasedExpenseCurrent_1460" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PrepaidStockBasedExpenseNoncurrent" xlink:label="loc_PPCBPrepaidStockBasedExpenseNoncurrent_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBPrepaidStockBasedExpenseNoncurrent_1460" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1460" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnrecognizedRestrictedStockUnitsExpense" xlink:label="loc_PPCBUnrecognizedRestrictedStockUnitsExpense_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBUnrecognizedRestrictedStockUnitsExpense_1460" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested_1460" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharePrice_1460" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaapFairValueAdjustmentOfWarrants_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapFairValueAdjustmentOfWarrants_1460" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_1460" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1460" xlink:type="arc" order="44" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1460" xlink:type="arc" order="45" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_1460" xlink:type="arc" order="46" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityReverseStockSplit" xlink:label="loc_us-gaapStockholdersEquityReverseStockSplit_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockholdersEquityReverseStockSplit_1460" xlink:type="arc" order="47" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SubscriptionReceivableValue" xlink:label="loc_PPCBSubscriptionReceivableValue_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBSubscriptionReceivableValue_1460" xlink:type="arc" order="48" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction" xlink:label="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_1460" xlink:type="arc" order="49" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_1460" xlink:type="arc" order="50" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AgreementTerm" xlink:label="loc_PPCBAgreementTerm_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBAgreementTerm_1460" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_EquityLineAgreementDrawdownNoticeDescription" xlink:label="loc_PPCBEquityLineAgreementDrawdownNoticeDescription_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBEquityLineAgreementDrawdownNoticeDescription_1460" xlink:type="arc" order="52" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SubscriptionReceivable" xlink:label="loc_PPCBSubscriptionReceivable_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBSubscriptionReceivable_1460" xlink:type="arc" order="53" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_1460" xlink:type="arc" order="54" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfAverageDailyTradingVolume" xlink:label="loc_PPCBPercentageOfAverageDailyTradingVolume_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBPercentageOfAverageDailyTradingVolume_1460" xlink:type="arc" order="55" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_BeneficialOwnershipLimitationPercentage" xlink:label="loc_PPCBBeneficialOwnershipLimitationPercentage_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBBeneficialOwnershipLimitationPercentage_1460" xlink:type="arc" order="56" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights1" xlink:label="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights1_1460" xlink:type="arc" order="57" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights2" xlink:label="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights2_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsOrRights2_1460" xlink:type="arc" order="58" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ClassOfWarrantOrRightAlternateExercisePriceOfWarrantsAtHolderOption" xlink:label="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsAtHolderOption_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBClassOfWarrantOrRightAlternateExercisePriceOfWarrantsAtHolderOption_1460" xlink:type="arc" order="59" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfExercisePriceAndMarketPrice" xlink:label="loc_PPCBPercentageOfExercisePriceAndMarketPrice_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBPercentageOfExercisePriceAndMarketPrice_1460" xlink:type="arc" order="60" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DeemedDividend" xlink:label="loc_PPCBDeemedDividend_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBDeemedDividend_1460" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionOriginalDebtAmount1" xlink:label="loc_us-gaapDebtConversionOriginalDebtAmount1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtConversionOriginalDebtAmount1_1460" xlink:type="arc" order="63" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockAmountIssued1" xlink:label="loc_us-gaapConversionOfStockAmountIssued1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapConversionOfStockAmountIssued1_1460" xlink:type="arc" order="64" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PrepaidShareBasedCompensation" xlink:label="loc_PPCBPrepaidShareBasedCompensation_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBPrepaidShareBasedCompensation_1460" xlink:type="arc" order="66" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensation_1460" xlink:type="arc" order="67" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1460" xlink:type="arc" order="68" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SettlementOfAccountsPayableForSharesOfCommonStock" xlink:label="loc_PPCBSettlementOfAccountsPayableForSharesOfCommonStock_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBSettlementOfAccountsPayableForSharesOfCommonStock_1460" xlink:type="arc" order="69" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_CommonStockIssuableShares" xlink:label="loc_PPCBCommonStockIssuableShares_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBCommonStockIssuableShares_1460" xlink:type="arc" order="70" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SettlementOfLoansForSharesOfCommonStock" xlink:label="loc_PPCBSettlementOfLoansForSharesOfCommonStock_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBSettlementOfLoansForSharesOfCommonStock_1460" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayable" xlink:label="loc_us-gaapLoansPayable_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapLoansPayable_1460" xlink:type="arc" order="72" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement" xlink:label="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueIssuanceOfCommonStockRelatedToWarrantExchangeAgreement_1460" xlink:type="arc" order="73" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TradingGainsLosses" xlink:label="loc_us-gaapTradingGainsLosses_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapTradingGainsLosses_1460" xlink:type="arc" order="74" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_EquityPurchaseAgreementDescription" xlink:label="loc_PPCBEquityPurchaseAgreementDescription_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBEquityPurchaseAgreementDescription_1460" xlink:type="arc" order="75" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingTerm" xlink:label="loc_us-gaapWarrantsAndRightsOutstandingTerm_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapWarrantsAndRightsOutstandingTerm_1460" xlink:type="arc" order="76" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightReasonForIssuingToNonemployees" xlink:label="loc_us-gaapClassOfWarrantOrRightReasonForIssuingToNonemployees_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightReasonForIssuingToNonemployees_1460" xlink:type="arc" order="77" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_1460" xlink:type="arc" order="78" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays" xlink:label="loc_us-gaapDebtInstrumentConvertibleThresholdTradingDays_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleThresholdTradingDays_1460" xlink:type="arc" order="79" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfWarrants" xlink:label="loc_us-gaapProceedsFromIssuanceOfWarrants_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfWarrants_1460" xlink:type="arc" order="80" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_StockIssuedDuringPeriodValueExerciseOfWarrants" xlink:label="loc_PPCBStockIssuedDuringPeriodValueExerciseOfWarrants_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_PPCBStockIssuedDuringPeriodValueExerciseOfWarrants_1460" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssued1" xlink:label="loc_us-gaapStockIssued1_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssued1_1460" xlink:type="arc" order="82" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaapDebtInstrumentTerm_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentTerm_1460" xlink:type="arc" order="83" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_1460" xlink:type="arc" order="84" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantExercisePriceIncrease" xlink:label="loc_us-gaapWarrantExercisePriceIncrease_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapWarrantExercisePriceIncrease_1460" xlink:type="arc" order="85" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMeasurementInput" xlink:label="loc_us-gaapDebtInstrumentMeasurementInput_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtInstrumentMeasurementInput_1460" xlink:type="arc" order="86" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaapCommonStockSharesIssued_1460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockSharesIssued_1460" xlink:type="arc" order="87" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:title="999053 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductLiabilityContingencyTable" xlink:label="loc_us-gaapProductLiabilityContingencyTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProductLiabilityContingencyTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaapLossContingenciesByNatureOfContingencyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapLossContingenciesByNatureOfContingencyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaapLossContingencyNatureDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapLossContingenciesByNatureOfContingencyAxis" xlink:to="loc_us-gaapLossContingencyNatureDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaapLossContingencyNatureDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLossContingenciesByNatureOfContingencyAxis" xlink:to="loc_us-gaapLossContingencyNatureDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndemnificationGuaranteeMember" xlink:label="loc_us-gaapIndemnificationGuaranteeMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLossContingencyNatureDomain" xlink:to="loc_us-gaapIndemnificationGuaranteeMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateAxis" xlink:label="loc_us-gaapAwardDateAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapAwardDateAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaapAwardDateDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardDateAxis" xlink:to="loc_us-gaapAwardDateDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaapAwardDateDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardDateAxis" xlink:to="loc_us-gaapAwardDateDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_From2012ThroughThe2014Member" xlink:label="loc_PPCBFrom2012ThroughThe2014Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBFrom2012ThroughThe2014Member_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InstallmentOneMember" xlink:label="loc_PPCBInstallmentOneMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBInstallmentOneMember_80" xlink:type="arc" order="82" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InstallmentTwoMember" xlink:label="loc_PPCBInstallmentTwoMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBInstallmentTwoMember_90" xlink:type="arc" order="92" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InstallmentThreeMember" xlink:label="loc_PPCBInstallmentThreeMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBInstallmentThreeMember_100" xlink:type="arc" order="102" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InstallmentFourMember" xlink:label="loc_PPCBInstallmentFourMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBInstallmentFourMember_110" xlink:type="arc" order="112" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InstallmentFiveMember" xlink:label="loc_PPCBInstallmentFiveMember_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAwardDateDomain" xlink:to="loc_PPCBInstallmentFiveMember_190" xlink:type="arc" order="191" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RoyaltyAgreementTermsMember" xlink:label="loc_us-gaapRoyaltyAgreementTermsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_us-gaapRoyaltyAgreementTermsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseAgreementTermsMember" xlink:label="loc_us-gaapLicenseAgreementTermsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_us-gaapLicenseAgreementTermsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OneYearCollaborationAgreementMember" xlink:label="loc_PPCBOneYearCollaborationAgreementMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBOneYearCollaborationAgreementMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_TwoYearCollaborationAgreementMember" xlink:label="loc_PPCBTwoYearCollaborationAgreementMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBTwoYearCollaborationAgreementMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ResearchAgreementMember" xlink:label="loc_PPCBResearchAgreementMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBResearchAgreementMember_140" xlink:type="arc" order="142" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnderwritingAgreementMember" xlink:label="loc_PPCBUnderwritingAgreementMember_310" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBUnderwritingAgreementMember_310" xlink:type="arc" order="311" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingAgreementMember" xlink:label="loc_PPCBConsultingAgreementMember_400" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBConsultingAgreementMember_400" xlink:type="arc" order="401" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AdvisoryAgreementMember" xlink:label="loc_PPCBAdvisoryAgreementMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBAdvisoryAgreementMember_420" xlink:type="arc" order="421" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NewThreeYearOperatingLeaseAgreementMember" xlink:label="loc_PPCBNewThreeYearOperatingLeaseAgreementMember_440" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBNewThreeYearOperatingLeaseAgreementMember_440" xlink:type="arc" order="441" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NewOneYearOperatingLeaseAgreementMember" xlink:label="loc_PPCBNewOneYearOperatingLeaseAgreementMember_480" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBNewOneYearOperatingLeaseAgreementMember_480" xlink:type="arc" order="481" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MergerAcquisitionAgreementMember" xlink:label="loc_PPCBMergerAcquisitionAgreementMember_630" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBMergerAcquisitionAgreementMember_630" xlink:type="arc" order="632" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InitialPayableMember" xlink:label="loc_PPCBInitialPayableMember_640" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBInitialPayableMember_640" xlink:type="arc" order="642" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UniversityOfJaenMember" xlink:label="loc_PPCBUniversityOfJaenMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBUniversityOfJaenMember_120" xlink:type="arc" order="121" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_EFHuttonLLCMember" xlink:label="loc_PPCBEFHuttonLLCMember_550" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBEFHuttonLLCMember_550" xlink:type="arc" order="552" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_270" xlink:type="arc" order="272" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_320" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_320" xlink:type="arc" order="322" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RepresentativesWarrantsMember" xlink:label="loc_PPCBRepresentativesWarrantsMember_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_PPCBRepresentativesWarrantsMember_340" xlink:type="arc" order="342" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_EquityAndEquityLinkedPlacementsMember" xlink:label="loc_PPCBEquityAndEquityLinkedPlacementsMember_560" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBEquityAndEquityLinkedPlacementsMember_560" xlink:type="arc" order="561" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtPlacementsMember" xlink:label="loc_PPCBDebtPlacementsMember_570" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBDebtPlacementsMember_570" xlink:type="arc" order="571" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_600" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_600" xlink:type="arc" order="601" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultantMember" xlink:label="loc_PPCBConsultantMember_610" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_PPCBConsultantMember_610" xlink:type="arc" order="611" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapProductLiabilityContingencyTable" xlink:to="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaapTypeOfAdoptionMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:to="loc_us-gaapTypeOfAdoptionMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaapTypeOfAdoptionMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:to="loc_us-gaapTypeOfAdoptionMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AccountingStandardUpdate201602Member" xlink:label="loc_PPCBAccountingStandardUpdate201602Member_700" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTypeOfAdoptionMember" xlink:to="loc_PPCBAccountingStandardUpdate201602Member_700" xlink:type="arc" order="701" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSought" xlink:label="loc_us-gaapLossContingencyDamagesSought_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLossContingencyDamagesSought_720" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PenaltyAmount" xlink:label="loc_PPCBPenaltyAmount_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBPenaltyAmount_720" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OperatingLeasesIncomeStatementRevenuePercentage" xlink:label="loc_PPCBOperatingLeasesIncomeStatementRevenuePercentage_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBOperatingLeasesIncomeStatementRevenuePercentage_720" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PaymentForServices" xlink:label="loc_PPCBPaymentForServices_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBPaymentForServices_720" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RoyaltyPercentage" xlink:label="loc_PPCBRoyaltyPercentage_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBRoyaltyPercentage_720" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RoyaltiesPercentage" xlink:label="loc_PPCBRoyaltiesPercentage_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBRoyaltiesPercentage_720" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnreimbursedLabFees" xlink:label="loc_PPCBUnreimbursedLabFees_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBUnreimbursedLabFees_720" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_720" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_720" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaapSaleOfStockPricePerShare_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSaleOfStockPricePerShare_720" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_720" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForUnderwritingExpense" xlink:label="loc_us-gaapPaymentsForUnderwritingExpense_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPaymentsForUnderwritingExpense_720" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ProceedsFromSettlementAmount" xlink:label="loc_PPCBProceedsFromSettlementAmount_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBProceedsFromSettlementAmount_720" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfSettlement" xlink:label="loc_PPCBPercentageOfSettlement_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBPercentageOfSettlement_720" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SettlementExpense" xlink:label="loc_PPCBSettlementExpense_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBSettlementExpense_720" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MonthlyFeeForServices" xlink:label="loc_PPCBMonthlyFeeForServices_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBMonthlyFeeForServices_720" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_720" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_720" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="loc_us-gaapLesseeOperatingLeaseTermOfContract_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLesseeOperatingLeaseTermOfContract_720" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRent" xlink:label="loc_us-gaapPaymentsForRent_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPaymentsForRent_720" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset_720" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaapOperatingLeaseLiability_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLeaseLiability_720" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_IncrementalBorrowingRate" xlink:label="loc_PPCBIncrementalBorrowingRate_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBIncrementalBorrowingRate_720" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaapOperatingLeaseWeightedAverageRemainingLeaseTerm1_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingLeaseWeightedAverageRemainingLeaseTerm1_720" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_720" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_720" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction" xlink:label="loc_us-gaapSaleOfStockPercentageOfOwnershipAfterTransaction_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSaleOfStockPercentageOfOwnershipAfterTransaction_720" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingTerm" xlink:label="loc_us-gaapWarrantsAndRightsOutstandingTerm_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapWarrantsAndRightsOutstandingTerm_720" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPrepaidExpenseCurrent_720" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredOfferingCosts" xlink:label="loc_us-gaapDeferredOfferingCosts_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDeferredOfferingCosts_720" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:label="loc_us-gaapLesseeOperatingLeaseRenewalTerm_720" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLesseeOperatingLeaseRenewalTerm_720" xlink:type="arc" order="30" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfRightOfUseAssetDetails" xlink:title="999054 - Disclosure - SCHEDULE OF RIGHT OF USE ASSET (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OperatingLeaseRightOfUseAssets" xlink:label="loc_PPCBOperatingLeaseRightOfUseAssets_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBOperatingLeaseRightOfUseAssets_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AccumulatedReduction" xlink:label="loc_PPCBAccumulatedReduction_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBAccumulatedReduction_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset_50" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfOperatingLeaseLiabilityDetails" xlink:title="999055 - Disclosure - SCHEDULE OF OPERATING LEASE LIABILITY (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OfficeLeaseLiability" xlink:label="loc_PPCBOfficeLeaseLiability_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBOfficeLeaseLiability_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ReductionOfLeaseLiability" xlink:label="loc_PPCBReductionOfLeaseLiability_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBReductionOfLeaseLiability_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapOperatingLeaseLiabilityCurrent_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityNoncurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapOperatingLeaseLiabilityNoncurrent_50" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfFutureMinimumLeasePaymentsDetails" xlink:title="999056 - Disclosure - SCHEDULE OF FUTURE MINIMUM LEASE PAYMENTS (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/RelatedPartyTransactionsDetailsNarrative" xlink:title="999057 - Disclosure - RELATED PARTY TRANSACTIONS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="loc_us-gaapRelatedPartyTransactionLineItems" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RelatedPartyTransactionsTable" xlink:label="loc_PPCBRelatedPartyTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBRelatedPartyTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NorthHorizonPtyLtdMember" xlink:label="loc_PPCBNorthHorizonPtyLtdMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBNorthHorizonPtyLtdMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NathanielszMember" xlink:label="loc_PPCBNathanielszMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBNathanielszMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapInvestorMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_140" xlink:type="arc" order="141" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MrsNathanielszMember" xlink:label="loc_PPCBMrsNathanielszMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBMrsNathanielszMember_250" xlink:type="arc" order="251" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MrNathanielszMember" xlink:label="loc_PPCBMrNathanielszMember_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBMrNathanielszMember_260" xlink:type="arc" order="261" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DrKenyonMember" xlink:label="loc_PPCBDrKenyonMember_360" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBDrKenyonMember_360" xlink:type="arc" order="362" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorMember" xlink:label="loc_PPCBFormerDirectorMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorMember_420" xlink:type="arc" order="421" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_FormerDirectorsMember" xlink:label="loc_PPCBFormerDirectorsMember_440" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBFormerDirectorsMember_440" xlink:type="arc" order="441" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_JamesNathanielszMember" xlink:label="loc_PPCBJamesNathanielszMember_710" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBJamesNathanielszMember_710" xlink:type="arc" order="711" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NewThreeYearOperatingLeaseAgreementMember" xlink:label="loc_PPCBNewThreeYearOperatingLeaseAgreementMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBNewThreeYearOperatingLeaseAgreementMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ThreeYearOperatingLeaseAgreementMember" xlink:label="loc_PPCBThreeYearOperatingLeaseAgreementMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBThreeYearOperatingLeaseAgreementMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OneYearOperatingLeaseAgreementMember" xlink:label="loc_PPCBOneYearOperatingLeaseAgreementMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBOneYearOperatingLeaseAgreementMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NathanielszEmploymentAgreementMember" xlink:label="loc_PPCBNathanielszEmploymentAgreementMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBNathanielszEmploymentAgreementMember_180" xlink:type="arc" order="181" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MrsNathanielszMember" xlink:label="loc_PPCBMrsNathanielszMember_280" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBMrsNathanielszMember_280" xlink:type="arc" order="282" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ServicesAgreementMember" xlink:label="loc_PPCBServicesAgreementMember_360" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBServicesAgreementMember_360" xlink:type="arc" order="361" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_EmploymentAgreementMember" xlink:label="loc_PPCBEmploymentAgreementMember_370" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBEmploymentAgreementMember_370" xlink:type="arc" order="371" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtExchangeMember" xlink:label="loc_PPCBDebtExchangeMember_460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBDebtExchangeMember_460" xlink:type="arc" order="462" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LoanAgreementMember" xlink:label="loc_PPCBLoanAgreementMember_550" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBLoanAgreementMember_550" xlink:type="arc" order="551" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LetterAgreementMember" xlink:label="loc_PPCBLetterAgreementMember_640" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBLetterAgreementMember_640" xlink:type="arc" order="641" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_200" xlink:type="arc" order="202" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_210" xlink:type="arc" order="212" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_BoardOfDirectorsMember" xlink:label="loc_PPCBBoardOfDirectorsMember_260" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_PPCBBoardOfDirectorsMember_260" xlink:type="arc" order="262" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ChiefExecutiveOfficerMember" xlink:label="loc_srtChiefExecutiveOfficerMember_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtChiefExecutiveOfficerMember_270" xlink:type="arc" order="271" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaapTypeOfAdoptionMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:to="loc_us-gaapTypeOfAdoptionMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaapTypeOfAdoptionMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAdjustmentsForNewAccountingPronouncementsAxis" xlink:to="loc_us-gaapTypeOfAdoptionMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AccountingStandardUpdate201602Member" xlink:label="loc_PPCBAccountingStandardUpdate201602Member_470" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTypeOfAdoptionMember" xlink:to="loc_PPCBAccountingStandardUpdate201602Member_470" xlink:type="arc" order="471" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_PPCBRelatedPartyTransactionsTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_590" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_590" xlink:type="arc" order="591" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="loc_us-gaapLesseeOperatingLeaseTermOfContract_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapLesseeOperatingLeaseTermOfContract_820" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LeasesRentExpenseMinimumRentals" xlink:label="loc_PPCBLeasesRentExpenseMinimumRentals_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBLeasesRentExpenseMinimumRentals_820" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_GoodsAndServiceTax" xlink:label="loc_PPCBGoodsAndServiceTax_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBGoodsAndServiceTax_820" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LeasesFutureMinimumPaymentsDue" xlink:label="loc_PPCBLeasesFutureMinimumPaymentsDue_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBLeasesFutureMinimumPaymentsDue_820" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseDescription" xlink:label="loc_us-gaapLesseeOperatingLeaseDescription_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapLesseeOperatingLeaseDescription_820" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRent" xlink:label="loc_us-gaapPaymentsForRent_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapPaymentsForRent_820" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RentPayable" xlink:label="loc_PPCBRentPayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBRentPayable_820" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_820" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="loc_us-gaapDebtInstrumentPeriodicPaymentPrincipal_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentPeriodicPaymentPrincipal_820" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:label="loc_us-gaapDebtInstrumentPeriodicPaymentInterest_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentPeriodicPaymentInterest_820" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableCurrent" xlink:label="loc_us-gaapLoansPayableCurrent_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapLoansPayableCurrent_820" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermLoansPayable" xlink:label="loc_us-gaapLongTermLoansPayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapLongTermLoansPayable_820" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDate" xlink:label="loc_us-gaapRelatedPartyTransactionDate_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapRelatedPartyTransactionDate_820" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_BaseSalaryPerMonth" xlink:label="loc_PPCBBaseSalaryPerMonth_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBBaseSalaryPerMonth_820" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalariesAndWages" xlink:label="loc_us-gaapSalariesAndWages_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapSalariesAndWages_820" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfPensionOfMonthlySalary" xlink:label="loc_PPCBPercentageOfPensionOfMonthlySalary_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBPercentageOfPensionOfMonthlySalary_820" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PercentageOfBonusOfAnnualBaseSalary" xlink:label="loc_PPCBPercentageOfBonusOfAnnualBaseSalary_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBPercentageOfBonusOfAnnualBaseSalary_820" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OfficersCompensation" xlink:label="loc_us-gaapOfficersCompensation_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapOfficersCompensation_820" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_BonusPayable" xlink:label="loc_PPCBBonusPayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBBonusPayable_820" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentSharesIssued1_820" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RemainingBonusAmount" xlink:label="loc_PPCBRemainingBonusAmount_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBRemainingBonusAmount_820" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_RemainingBalanceOfBonusPayable" xlink:label="loc_PPCBRemainingBalanceOfBonusPayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBRemainingBalanceOfBonusPayable_820" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_AgreementTerm" xlink:label="loc_PPCBAgreementTerm_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBAgreementTerm_820" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_820" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdministrativeFeePayable" xlink:label="loc_us-gaapAdministrativeFeePayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapAdministrativeFeePayable_820" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedSalariesCurrent" xlink:label="loc_us-gaapAccruedSalariesCurrent_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapAccruedSalariesCurrent_820" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_820" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaapOtherLiabilitiesCurrent_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapOtherLiabilitiesCurrent_820" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_820" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SettlementOfLoansForSharesOfCommonStock" xlink:label="loc_PPCBSettlementOfLoansForSharesOfCommonStock_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBSettlementOfLoansForSharesOfCommonStock_820" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OperatingLeasesRentExpenseMinimumRental" xlink:label="loc_PPCBOperatingLeasesRentExpenseMinimumRental_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBOperatingLeasesRentExpenseMinimumRental_820" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_OperatingLeaseFutureMinimumPaymentsDue" xlink:label="loc_PPCBOperatingLeaseFutureMinimumPaymentsDue_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_PPCBOperatingLeaseFutureMinimumPaymentsDue_820" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_820" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_820" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_820" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger" xlink:label="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_820" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfBankDebt" xlink:label="loc_us-gaapRepaymentsOfBankDebt_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapRepaymentsOfBankDebt_820" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayable" xlink:label="loc_us-gaapLoansPayable_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapLoansPayable_820" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaapDebtInstrumentTerm_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapDebtInstrumentTerm_820" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_820" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_820" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfRelatedPartyDebt" xlink:label="loc_us-gaapRepaymentsOfRelatedPartyDebt_820" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapRepaymentsOfRelatedPartyDebt_820" xlink:type="arc" order="41" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ConcentrationsAndRisksDetailsNarrative" xlink:title="999058 - Disclosure - CONCENTRATIONS AND RISKS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaapConcentrationRiskLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaapConcentrationRiskTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskLineItems" xlink:to="loc_us-gaapConcentrationRiskTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapConcentrationRiskTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderOneMember" xlink:label="loc_PPCBLenderOneMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBLenderOneMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderTwoMember" xlink:label="loc_PPCBLenderTwoMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBLenderTwoMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderThreeMember" xlink:label="loc_PPCBLenderThreeMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBLenderThreeMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderFourMember" xlink:label="loc_PPCBLenderFourMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBLenderFourMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderFiveMember" xlink:label="loc_PPCBLenderFiveMember_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_PPCBLenderFiveMember_230" xlink:type="arc" order="231" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaapConcentrationRiskByBenchmarkAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapConcentrationRiskTable" xlink:to="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaapConcentrationRiskBenchmarkDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:to="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaapConcentrationRiskBenchmarkDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:to="loc_us-gaapConcentrationRiskBenchmarkDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConvertibleDebtBenchmarkMember" xlink:label="loc_PPCBConvertibleDebtBenchmarkMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:to="loc_PPCBConvertibleDebtBenchmarkMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaapAccountsReceivableMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:to="loc_us-gaapAccountsReceivableMember_160" xlink:type="arc" order="161" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaapConcentrationRiskByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapConcentrationRiskTable" xlink:to="loc_us-gaapConcentrationRiskByTypeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LenderConcentrationRiskMember" xlink:label="loc_us-gaapLenderConcentrationRiskMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskTypeDomain" xlink:to="loc_us-gaapLenderConcentrationRiskMember_40" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditConcentrationRiskMember" xlink:label="loc_us-gaapCreditConcentrationRiskMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskTypeDomain" xlink:to="loc_us-gaapCreditConcentrationRiskMember_160" xlink:type="arc" order="162" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis" xlink:label="loc_srtMajorCustomersAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapConcentrationRiskTable" xlink:to="loc_srtMajorCustomersAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srtNameOfMajorCustomerDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtMajorCustomersAxis" xlink:to="loc_srtNameOfMajorCustomerDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srtNameOfMajorCustomerDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtMajorCustomersAxis" xlink:to="loc_srtNameOfMajorCustomerDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderOneMember" xlink:label="loc_PPCBLenderOneMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBLenderOneMember_40" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderTwoMember" xlink:label="loc_PPCBLenderTwoMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBLenderTwoMember_50" xlink:type="arc" order="53" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderThreeMember" xlink:label="loc_PPCBLenderThreeMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBLenderThreeMember_60" xlink:type="arc" order="63" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderFourMember" xlink:label="loc_PPCBLenderFourMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBLenderFourMember_150" xlink:type="arc" order="153" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ReceivableMember" xlink:label="loc_PPCBReceivableMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBReceivableMember_160" xlink:type="arc" order="163" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_LenderFiveMember" xlink:label="loc_PPCBLenderFiveMember_280" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_PPCBLenderFiveMember_280" xlink:type="arc" order="283" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskLineItems" xlink:to="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts_420" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromConvertibleDebt" xlink:label="loc_us-gaapProceedsFromConvertibleDebt_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskLineItems" xlink:to="loc_us-gaapProceedsFromConvertibleDebt_420" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaapConcentrationRiskPercentage1_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskLineItems" xlink:to="loc_us-gaapConcentrationRiskPercentage1_420" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfFairValueMeasurementsRecurringAndNonrecurringValuationTechniquesDetails" xlink:title="999059 - Disclosure - SCHEDULE OF FAIR VALUE MEASUREMENTS, RECURRING AND NONRECURRING, VALUATION TECHNIQUES (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="loc_us-gaapDerivativeInstrumentsGainLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="loc_us-gaapMeasurementInputTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="loc_us-gaapMeasurementInputTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaapMeasurementInputTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapMeasurementInputTypeAxis" xlink:to="loc_us-gaapMeasurementInputTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="loc_us-gaapMeasurementInputPriceVolatilityMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputPriceVolatilityMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedTermMember" xlink:label="loc_us-gaapMeasurementInputExpectedTermMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputExpectedTermMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:label="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMeasurementInputTypeDomain" xlink:to="loc_us-gaapMeasurementInputRiskFreeInterestRateMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaapShortTermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="loc_us-gaapShortTermDebtTypeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaapConvertibleDebtMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_us-gaapConvertibleDebtMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaapDerivativeInstrumentRiskAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaapDerivativeContractTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:to="loc_us-gaapDerivativeContractTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaapDerivativeContractTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:to="loc_us-gaapDerivativeContractTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NewDerivativeInstrumentsMember" xlink:label="loc_PPCBNewDerivativeInstrumentsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeContractTypeDomain" xlink:to="loc_PPCBNewDerivativeInstrumentsMember_0" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_50" xlink:type="arc" order="54" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_60" xlink:type="arc" order="64" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMeasurementInput" xlink:label="loc_us-gaapDebtInstrumentMeasurementInput_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapDebtInstrumentMeasurementInput_270" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaapDebtInstrumentTerm_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapDebtInstrumentTerm_270" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails" xlink:title="999060 - Disclosure - SCHEDULE OF FAIR VALUE, ASSETS AND LIABILITIES MEASURED ON RECURRING BASIS (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaapFairValueInputsLevel1Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel1Member_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaapFairValueInputsLevel2Member_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel2Member_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaapFairValueInputsLevel3Member_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel3Member_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_WarrantLiability" xlink:label="loc_PPCBWarrantLiability_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBWarrantLiability_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="loc_us-gaapEmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapEmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaapDerivativeLiabilities_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapDerivativeLiabilities_130" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ScheduleOfDerivativeLiabilitiesAtFairValueDetails" xlink:title="999061 - Disclosure - SCHEDULE OF DERIVATIVE LIABILITIES AT FAIR VALUE (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:label="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:label="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaapFinancialInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:to="loc_us-gaapFinancialInstrumentAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember" xlink:label="loc_us-gaapDerivativeMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_us-gaapDerivativeMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaapDerivativeLiabilities_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapDerivativeLiabilities_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmbeddedDerivativeGainOnEmbeddedDerivative" xlink:label="loc_us-gaapEmbeddedDerivativeGainOnEmbeddedDerivative_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapEmbeddedDerivativeGainOnEmbeddedDerivative_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmbeddedDerivativeLossOnEmbeddedDerivative" xlink:label="loc_us-gaapEmbeddedDerivativeLossOnEmbeddedDerivative_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapEmbeddedDerivativeLossOnEmbeddedDerivative_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_80" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:label="loc_us-gaapDerivativeGainLossOnDerivativeNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapDerivativeGainLossOnDerivativeNet_80" xlink:type="arc" order="4" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SummaryOfChangesInFairValueOfLevel3WarrantLiabilityDetails" xlink:title="999062 - Disclosure - SUMMARY OF THE CHANGES IN THE FAIR VALUE OF THE LEVEL 3 WARRANT LIABILITY (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaapFairValueInputsLevel3Member_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel3Member_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstanding" xlink:label="loc_us-gaapWarrantsAndRightsOutstanding_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapWarrantsAndRightsOutstanding_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InitialFairValueOfWarrantLiabilityUponIssuance" xlink:label="loc_PPCBInitialFairValueOfWarrantLiabilityUponIssuance_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBInitialFairValueOfWarrantLiabilityUponIssuance_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_InitialFairValuationOfWarrantLiability" xlink:label="loc_PPCBInitialFairValuationOfWarrantLiability_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_PPCBInitialFairValuationOfWarrantLiability_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaapFairValueAdjustmentOfWarrants_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDefinedBenefitPlanDisclosureLineItems" xlink:to="loc_us-gaapFairValueAdjustmentOfWarrants_40" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/DerivativeFinancialInstrumentsAndFairValueMeasurementsDetailsNarrative" xlink:title="999063 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="loc_us-gaapDerivativeInstrumentsGainLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaapDerivativeInstrumentRiskAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaapDerivativeContractTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:to="loc_us-gaapDerivativeContractTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaapDerivativeContractTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDerivativeInstrumentRiskAxis" xlink:to="loc_us-gaapDerivativeContractTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaapConvertibleDebtMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeContractTypeDomain" xlink:to="loc_us-gaapConvertibleDebtMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebt" xlink:label="loc_us-gaapConvertibleDebt_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapConvertibleDebt_60" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDerivativeInstrumentsGainLossLineItems" xlink:to="loc_us-gaapSharePrice_60" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/SubsequentEventsDetailsNarrative" xlink:title="999064 - Disclosure - SUBSEQUENT EVENTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaapSubsequentEventTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSubsequentEventTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapWarrantMember_150" xlink:type="arc" order="154" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="loc_us-gaapSeriesCPreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesCPreferredStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SeriesCWarrantsMember" xlink:label="loc_PPCBSeriesCWarrantsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_PPCBSeriesCWarrantsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_GSCapitalPartnersLLCMember" xlink:label="loc_PPCBGSCapitalPartnersLLCMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBGSCapitalPartnersLLCMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ThousandEightHundredDiagonalLendingLLCMember" xlink:label="loc_PPCBThousandEightHundredDiagonalLendingLLCMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBThousandEightHundredDiagonalLendingLLCMember_90" xlink:type="arc" order="93" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DBoralCapitalLLCMember" xlink:label="loc_PPCBDBoralCapitalLLCMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_PPCBDBoralCapitalLLCMember_130" xlink:type="arc" order="133" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_SecuritiesPurchaseAgreementMember" xlink:label="loc_PPCBSecuritiesPurchaseAgreementMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBSecuritiesPurchaseAgreementMember_60" xlink:type="arc" order="62" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_UnderwritingAgreementMember" xlink:label="loc_PPCBUnderwritingAgreementMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBUnderwritingAgreementMember_130" xlink:type="arc" order="132" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ConsultingAgreementMember" xlink:label="loc_PPCBConsultingAgreementMember_310" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_PPCBConsultingAgreementMember_310" xlink:type="arc" order="311" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_us-gaapInvestorMember_70" xlink:type="arc" order="72" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember" xlink:label="loc_srtDirectorMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtDirectorMember_110" xlink:type="arc" order="112" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_170" xlink:type="arc" order="175" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_180" xlink:type="arc" order="185" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaapSubsidiarySaleOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaapSaleOfStockNameOfTransactionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:to="loc_us-gaapSaleOfStockNameOfTransactionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaapSaleOfStockNameOfTransactionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsidiarySaleOfStockAxis" xlink:to="loc_us-gaapSaleOfStockNameOfTransactionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OverAllotmentOptionMember" xlink:label="loc_us-gaapOverAllotmentOptionMember_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSaleOfStockNameOfTransactionDomain" xlink:to="loc_us-gaapOverAllotmentOptionMember_190" xlink:type="arc" order="194" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IPOMember" xlink:label="loc_us-gaapIPOMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSaleOfStockNameOfTransactionDomain" xlink:to="loc_us-gaapIPOMember_200" xlink:type="arc" order="202" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaapShortTermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapShortTermDebtTypeAxis" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaapConvertibleDebtMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_us-gaapConvertibleDebtMember_210" xlink:type="arc" order="212" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableMember" xlink:label="loc_us-gaapLoansPayableMember_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_us-gaapLoansPayableMember_230" xlink:type="arc" order="231" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PromissoryNotesOneMember" xlink:label="loc_PPCBPromissoryNotesOneMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_PPCBPromissoryNotesOneMember_250" xlink:type="arc" order="252" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember" xlink:label="loc_us-gaapRelatedPartyMember_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapRelatedPartyMember_290" xlink:type="arc" order="292" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_340" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaapConversionOfStockSharesConverted1_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapConversionOfStockSharesConverted1_340" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="loc_us-gaapProceedsFromWarrantExercises_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProceedsFromWarrantExercises_340" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_340" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_340" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_340" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockConvertibleSharesIssuable" xlink:label="loc_us-gaapPreferredStockConvertibleSharesIssuable_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPreferredStockConvertibleSharesIssuable_340" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_340" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepurchaseAmount" xlink:label="loc_us-gaapDebtInstrumentRepurchaseAmount_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentRepurchaseAmount_340" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_340" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_340" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateEffectivePercentage_340" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentPaymentTerms" xlink:label="loc_us-gaapDebtInstrumentPaymentTerms_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentPaymentTerms_340" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_340" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaapDeferredFinanceCostsNet_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDeferredFinanceCostsNet_340" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentDebtConversionRate" xlink:label="loc_PPCBDebtInstrumentDebtConversionRate_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBDebtInstrumentDebtConversionRate_340" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentDiscountRate" xlink:label="loc_PPCBDebtInstrumentDiscountRate_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBDebtInstrumentDiscountRate_340" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_340" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaapSaleOfStockPricePerShare_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSaleOfStockPricePerShare_340" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable" xlink:label="loc_us-gaapClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable_340" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfCommonStock_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfCommonStock_340" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_NetProceedsFromIssuanceOfCommonStock" xlink:label="loc_PPCBNetProceedsFromIssuanceOfCommonStock_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBNetProceedsFromIssuanceOfCommonStock_340" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_340" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_PenaltyAmount" xlink:label="loc_PPCBPenaltyAmount_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBPenaltyAmount_340" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="loc_us-gaapInterestPayableCurrentAndNoncurrent_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapInterestPayableCurrentAndNoncurrent_340" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFeeAmount" xlink:label="loc_us-gaapDebtInstrumentFeeAmount_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentFeeAmount_340" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_ReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital" xlink:label="loc_PPCBReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBReclassifiedFromPremiumLiabilitiesToAdditionalPaidInCapital_340" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepaidPrincipal" xlink:label="loc_us-gaapDebtInstrumentRepaidPrincipal_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtInstrumentRepaidPrincipal_340" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtDefaultLongtermDebtAmount" xlink:label="loc_us-gaapDebtDefaultLongtermDebtAmount_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapDebtDefaultLongtermDebtAmount_340" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_DebtInstrumentIssuanceDateDescription" xlink:label="loc_PPCBDebtInstrumentIssuanceDateDescription_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBDebtInstrumentIssuanceDateDescription_340" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaapRepaymentsOfLongTermDebt_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRepaymentsOfLongTermDebt_340" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="ppcb-20260331.xsd#PPCB_MonthlyFeeForServices" xlink:label="loc_PPCBMonthlyFeeForServices_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_PPCBMonthlyFeeForServices_340" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForFees" xlink:label="loc_us-gaapPaymentsForFees_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapPaymentsForFees_340" xlink:type="arc" order="32" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://propanc.com/role/ReverseStockSplitDetailsNarrative" xlink:title="999065 - Disclosure - REVERSE STOCK SPLIT (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaapSubsequentEventLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaapSubsequentEventTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapSubsequentEventTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityReverseStockSplit" xlink:label="loc_us-gaapStockholdersEquityReverseStockSplit_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapStockholdersEquityReverseStockSplit_20" xlink:type="arc" order="0" />
    </link:definitionLink>
</link:linkbase>
