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Asymmetric Self-Renewal By Distributed Stem Cells: Misunderstood in the Past, Important for the Future James L. Sherley, M.D., Ph.D. Director The Adult Stem Cell Technology Center, LLC Boston, MA, USA ASCTC
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Fetal, Neonatal, Adult DevelopmentEarlyEmbryonicDevelopment Fetal SCs Germline SCs Post-natal SCs Somatic SCs Tissue SCs Adult SCs Epiblasts [embryonic SCs] Embryonic precursors precursors EmbryonicPost-Embryonic Sources of Stem Cells (SCs) During Mammalian Development Distributed Stem Cells? (DSCs)
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Fetal SCs Germline SCs Post-natal SCs Somatic SCs Tissue SCs Adult SCs Embryonic Post-Embryonic “DISTRIBUTED STEM CELLS” DSCs (Sherley, 2008, Breast Disease 29, 37-46) For Distributed Potency Asymmetric Self-Renewal Asymmetric Self-Renewal In vivo and in vitro Embryonic stem cells Primordial germ cells Induced pluripotent SCs Symmetric Self-Renewal In vitro ASCTC
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The Pervasive Stem Cell Definition: Self-renewal or Differentiation ASCTC SymmetricSelf-renewal
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The Pervasive Stem Cell Definition: Self-renewal or Differentiation ASCTC SymmetricSelf-renewal An Inadequate Definition For Distributed Stem Cells
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A Gnomonic for Distributed Stem Cells: Self-renewal AND Differentiation, continuously and simultaneously ASCTC “AsymmetricSelf-renewal”
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Tissue Cell Turnover The mark of distributed stem cells (DSCs): Asymmetric Self-Renewal Potten et al., 2003 DeathTerminalArrestDifferentiationSymmetricKineticsAsymmetric Self-renewal Cell Kinetics DSC (niche) ASCTC
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A CENTRAL QUESTION: What is the cell kinetics form of asymmetric self-renewal? ASCTC
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Mathematical Identity, but Biological Distinctions p1-p Stochastic vs. Determined ASCTC
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Biological Distinctions Stochastic 1.Extinction probability 2.Mutation accrual Determined 1.No DSC differentiation 2.Individual asymmetric division 3.Mutation avoidance? 4.Unique cellular programs! p1-p vs. ASCTC
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≠ Developmental Asymmetric Divisions Are Not Equivalent to Asymmetric Self-Renewal Divisions Asymmetric Division Sisters unequal Sisters unequal Both sisters differ Both sisters differ from parent from parent Limited Limited Asymmetric Self-Renewal Sisters unequal Sisters unequal One sister equal One sister equal to parent to parent Continuous over lifespan Continuous over lifespan ASCTC
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Biological Distinctions Stochastic 1.Extinction probability 2.Mutation accrual Determined 1.No DSC differentiation 2.Individual asymmetric division 3.Mutation avoidance? 4.Unique cellular programs! p1-p vs. ASCTC
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+ Asymmetric Self-Renewal Associated (ASRA) Genes: Highly Specific Biomarkers for DSCs SYM ASYM [Noh et al. 2011, PLoS ONE] SYMASYM CyA CXCR6 DNA Phase [Taghizadeh et al., 2010, PLoS ONE] ASCTC
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Stem Cell Therapy “Adult” Stem Cells (DSCs) Embryonic Stem Cells (ESCs) Induced Pluripotent Stem Cells (iPSCs) Proposed Stem Cells for Tissue Replacement ASCTC
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Stochastic Deterministic (In Vitro) Self-Renewal OR Differentiation Stemness Preserved “AsymmetricSelf-Renewal” Embryonic and iP Stem Cells Distributed Stem Cells Mathematical Features of Cell Production with Differentiation p1-p a b d c Self-Renewal AND Differentiation Loss of Stemness a a ASCTC
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Stem Cell Therapy “Adult” Stem Cells (DSCs) Embryonic Stem Cells (ESCs) Induced Pluripotent Stem Cells (iPSCs) Proposed Stem Cells for Tissue Replacement ASCTC
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NormalTissue Damaged or Diseased Tissue Tissue Therapy with ESCs and iPSCs? REPAIR? ASCTC
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NormalTissue Damaged or Diseased Tissue Short-livedRepair!!!! (Tumors!) Tissue Therapy with ESCs and iPSCs hESCs and iPSCs - ethical issues (hESCs) - epigenetic defects - genetic defects Purification - ESCs! - iPSCs! - other differentiated cells “Develop In Vitro” Differentiated Cells (Immature) ASCTC
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NormalTissue Damaged or Diseased Tissue DSC Expansion is possible! Autologous Autologous Allogeneic Allogeneic Informed Consent Informed Consent RenewingRepairedTissue Tissue Therapy with Distributed Stem Cells - purity not required - expansion not always critical critical ASCTC
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NormalTissue Damaged or Diseased Tissue An DSC Bottleneck for Tissue Therapy “Develop In Vitro” Isolate, stabilize, expand Distributed Stem Cells RepairedTissue? Tumor Risk Remains [Sherley, J. L. 2004, J. Biomed. Biotech. 2, 71-72.] Differentiated Cells (Immature) hESCs and iPSCs - ethical issues (hESCs) - epigenetic defects - genetic defects ASCTC
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Distributed Stem Cell Asymmetric Self-Renewal Embryonic development hESCs? iPSCs Immature? ASCTC
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Distributed Stem Cell Asymmetric Self-Renewal Embryonic development hESCs? iPSCs Xanthine (p53-KO mimic) Immature? Pare & Sherley, 2011, J. Biomed. Biotech. New Patent: USPTO No. 8,759,098, June 24, 2014 ASCTC DiseaseResearch
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