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  <xsd:element id="selb_EarlyExtinguishmentOfDebtPrepaymentFeePercentage" name="EarlyExtinguishmentOfDebtPrepaymentFeePercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_EligiblePeriodToReceiveRoyalties" name="EligiblePeriodToReceiveRoyalties" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_EmployeeStockPurchasePlan2016Member" name="EmployeeStockPurchasePlan2016Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_EmployeeStockPurchasePlanMaximumPercentageOfSharesReservedBasedOnSharesOutstanding" name="EmployeeStockPurchasePlanMaximumPercentageOfSharesReservedBasedOnSharesOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_ExclusivePatentLicenseAgreementWithMassachusettsInstituteOfTechnologyMember" name="ExclusivePatentLicenseAgreementWithMassachusettsInstituteOfTechnologyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_FinalPaymentFeePercentage" name="FinalPaymentFeePercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_FirstAcquisitionRightMember" name="FirstAcquisitionRightMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_FirstGrantMember" name="FirstGrantMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_FounderMember" name="FounderMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_GrantRevenueAvailableUnderGrantNotRecognized" name="GrantRevenueAvailableUnderGrantNotRecognized" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_GrantsFromEntitiesAmountOfGrantAward" name="GrantsFromEntitiesAmountOfGrantAward" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_IncomeTaxHolidayTerm" name="IncomeTaxHolidayTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_IncreaseDecreaseInContingentlyRepayableGrantFunding" name="IncreaseDecreaseInContingentlyRepayableGrantFunding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_InitialLicenseFeePaid" name="InitialLicenseFeePaid" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_InvestmentsMaturityPeriod" name="InvestmentsMaturityPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LaboratoryAndOfficeSpaceMember" name="LaboratoryAndOfficeSpaceMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LaboratoryEquipmentMember" name="LaboratoryEquipmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAgreementWithMassachusettsEyeAndEarInfirmaryAndSchepensEyeResearchInstituteInc.Member" name="LicenseAgreementWithMassachusettsEyeAndEarInfirmaryAndSchepensEyeResearchInstituteInc.Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAgreementWithShenyangSunshinePharmaceuticalCompanyLimitedMember" name="LicenseAgreementWithShenyangSunshinePharmaceuticalCompanyLimitedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementAdditionalDevelopmentAndRegulatoryMilestonePaymentsThatMayBeReceived" name="LicenseAndOptionAgreementAdditionalDevelopmentAndRegulatoryMilestonePaymentsThatMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementAdditionalSubLicensePaymentReceivedLiability" name="LicenseAndOptionAgreementAdditionalSubLicensePaymentReceivedLiability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementAggregateAdditionalPaymentsDueWithinTwelveMonthsOfContractDate" name="LicenseAndOptionAgreementAggregateAdditionalPaymentsDueWithinTwelveMonthsOfContractDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementCalculatedPremiumPaidForEquityInvestmentUnderPurchaseAgreement" name="LicenseAndOptionAgreementCalculatedPremiumPaidForEquityInvestmentUnderPurchaseAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementCommercializationMilestonePaymentsThatMayBeReceived" name="LicenseAndOptionAgreementCommercializationMilestonePaymentsThatMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementContractualPaymentsMade" name="LicenseAndOptionAgreementContractualPaymentsMade" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementNumberOfAdditionalTargetsForWhichOtherPartyMayExerciseOptionsForAdditionalLicenses" name="LicenseAndOptionAgreementNumberOfAdditionalTargetsForWhichOtherPartyMayExerciseOptionsForAdditionalLicenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementPeriodForOtherPartyToExerciseOptionsForAdditionalLicenses" name="LicenseAndOptionAgreementPeriodForOtherPartyToExerciseOptionsForAdditionalLicenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementSalesMilestonePaymentsThatMayBeReceived" name="LicenseAndOptionAgreementSalesMilestonePaymentsThatMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementTwoPaymentsDueWithinTwelveMonthsOfContractDate" name="LicenseAndOptionAgreementTwoPaymentsDueWithinTwelveMonthsOfContractDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementUpfrontCashPayment" name="LicenseAndOptionAgreementUpfrontCashPayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_LicenseAndOptionAgreementVariableFeeToBeReceivedForEachAdditionalTargetOptionElected" name="LicenseAndOptionAgreementVariableFeeToBeReceivedForEachAdditionalTargetOptionElected" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_LicenseAndSupplyObligationMember" name="LicenseAndSupplyObligationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_MaximumPercentagePaidOnTieredRoyalties" name="MaximumPercentagePaidOnTieredRoyalties" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_NationalInstitutesOfHealthGrantAgreementMember" name="NationalInstitutesOfHealthGrantAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_NonEmployeeStockOptionMember" name="NonEmployeeStockOptionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_NumberOfAgreementsCombinedIntoSingleAgreementForEvaluation" name="NumberOfAgreementsCombinedIntoSingleAgreementForEvaluation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_NumberOfCollaborationAgreementsUnderAnalysisToQuantifyImpactOfAdoption" name="NumberOfCollaborationAgreementsUnderAnalysisToQuantifyImpactOfAdoption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_NumberOfOfferingPeriods" name="NumberOfOfferingPeriods" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_NumberOfProductsMarketedAndSold" name="NumberOfProductsMarketedAndSold" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_NumberOfWarrantsExercisedToPurchaseCommonStock" name="NumberOfWarrantsExercisedToPurchaseCommonStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_OfferingPeriod" name="OfferingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_PaymentAmountUponAchievementOfDefinedClinicalMilestones" name="PaymentAmountUponAchievementOfDefinedClinicalMilestones" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_PercentageOfEstimatedCostOfResearchPlan" name="PercentageOfEstimatedCostOfResearchPlan" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_PercentageOfSublicenseIncome" name="PercentageOfSublicenseIncome" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_PeriodForCommercializationOfProduct" name="PeriodForCommercializationOfProduct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_PeriodForPriorWrittenNoticeToTerminateLicense" name="PeriodForPriorWrittenNoticeToTerminateLicense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_PeriodToAuditExpenditureIncurred" name="PeriodToAuditExpenditureIncurred" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_PremiumOfAverageDailyVolumeWeightedAveragePriceOfCommonStockPercent" name="PremiumOfAverageDailyVolumeWeightedAveragePriceOfCommonStockPercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_PublicSecuritiesOfferingAmountAuthorized" name="PublicSecuritiesOfferingAmountAuthorized" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_PublicStockOfferingAmountAuthorized" name="PublicStockOfferingAmountAuthorized" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_RegulatoryMilestonesMember" name="RegulatoryMilestonesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_RemainingPercentageContributedByEntity" name="RemainingPercentageContributedByEntity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_ResearchAndDevelopmentMember" name="ResearchAndDevelopmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_RestrictedCashAndOtherDepositsMember" name="RestrictedCashAndOtherDepositsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_RevenueNumberOfPerformanceObligations" name="RevenueNumberOfPerformanceObligations" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_RevenueRemainingPerformanceObligationEachOption" name="RevenueRemainingPerformanceObligationEachOption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="selb_RevenueRemainingPerformanceObligationPercentage" name="RevenueRemainingPerformanceObligationPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_RussiaVasedDevelopmentFundOfNewTechnologiesDevelopmentAndCommercializationCenterGrantAgreementMember" name="RussiaVasedDevelopmentFundOfNewTechnologiesDevelopmentAndCommercializationCenterGrantAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_RussianFederalTaxServiceMember" name="RussianFederalTaxServiceMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_SalesMilestoneMethodAmountPaid" name="SalesMilestoneMethodAmountPaid" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_SecondAcquisitionRightMember" name="SecondAcquisitionRightMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_SeriesDRedeemableConvertiblePreferredStockMember" name="SeriesDRedeemableConvertiblePreferredStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_SeriesERedeemableConvertiblePreferredStockMember" name="SeriesERedeemableConvertiblePreferredStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeituresRate" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeituresRate" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantIncreaseDecrease" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantIncreaseDecrease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTermAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTermAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_ShareBasedCompensationArrangementByShareBasedPaymentAwardVotingRightsOfCommonStockHoldingPercentage" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardVotingRightsOfCommonStockHoldingPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_ShareBasedGoodsAndNonEmployeeServicesTransactionCompensationNotYetRecognizedStockOptions" name="ShareBasedGoodsAndNonEmployeeServicesTransactionCompensationNotYetRecognizedStockOptions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="selb_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedOutstandingIntrinsicValue" name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedOutstandingIntrinsicValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="selb_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedOutstandingWeightedAverageRemainingContractualTerm" name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedOutstandingWeightedAverageRemainingContractualTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedWeightedAverageExercisePrice" name="SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedWeightedAverageExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_SparkLetterAgreementMember" name="SparkLetterAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_SpringerPurchaseAgreementMember" name="SpringerPurchaseAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_StockIncentivePlan2008Member" name="StockIncentivePlan2008Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_StockIncentivePlan2016Member" name="StockIncentivePlan2016Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_StockIssuedDuringPeriodSharesCommonStockIssuedUponExerciseOfWarrants" name="StockIssuedDuringPeriodSharesCommonStockIssuedUponExerciseOfWarrants" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_StockPurchaseAgreementAuthorizedAmountOfStockToSell" name="StockPurchaseAgreementAuthorizedAmountOfStockToSell" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="selb_StockPurchaseProgramAggregatePurchasePricePerShare" name="StockPurchaseProgramAggregatePurchasePricePerShare" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_StockPurchaseProgramNumberOfSharesAuthorizedToBeSold" name="StockPurchaseProgramNumberOfSharesAuthorizedToBeSold" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_TaxCutsandJobsActChangeinTaxRateIncreaseDecreaseInDeferredTaxAsset" name="TaxCutsandJobsActChangeinTaxRateIncreaseDecreaseInDeferredTaxAsset" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="selb_TaxCutsandJobsActValuationAllowanceDeferredTaxAssetIncreaseDecreaseAmount" name="TaxCutsandJobsActValuationAllowanceDeferredTaxAssetIncreaseDecreaseAmount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="selb_TechnologyLicenseAgreementsTextBlock" name="TechnologyLicenseAgreementsTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_TermLoanMember" name="TermLoanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_TermLoanNumberofPayments" name="TermLoanNumberofPayments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_TermLoanPrepaidAfterFirstAnniversaryButBeforeSecondAnniversaryMember" name="TermLoanPrepaidAfterFirstAnniversaryButBeforeSecondAnniversaryMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_TermLoanPrepaidAfterSecondAnniversaryMember" name="TermLoanPrepaidAfterSecondAnniversaryMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_TermLoanPrepaidBeforetheFirstAnniversaryMember" name="TermLoanPrepaidBeforetheFirstAnniversaryMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_The2008PlanAndThe2016PlanMember" name="The2008PlanAndThe2016PlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="selb_UnrestrictedCashMember" name="UnrestrictedCashMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="selb_UpfrontAndMilestoneBasedPaymentsAdditionalLiability" name="UpfrontAndMilestoneBasedPaymentsAdditionalLiability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="selb_VotesPerShareofCommonStock" name="VotesPerShareofCommonStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="instant" />
  <xsd:element id="selb_WarrantsGrantDateFairValue" name="WarrantsGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="selb_WarrantsPolicyTextBlock" name="WarrantsPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
</xsd:schema>
