| ESCs | Induced pluripotent stem cells (iPSCs) | Bone marrow-derived stem cells (adult stem cells) | Umbilical cord lining epithelial stem cells |
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Source | • Pluripotent stem cell source • Controversial sourcing • Requires invasive procedure | • Pluripotent cells • Reprogrammed adult blood or dermal fibroblast cells • Inefficient generation procedure (0.01–1%) • Relatively expensive autologous transplantation procedure | • Multipotent stem cells • Derived using an invasive procedure • Potential risks and significant discomfort to the donor • Limited proliferative capacity • Aging at each doubling | • Multipotent stem cells • Source is medical waste and inexpensive • Devoid of maternal or fetal morbidity • Billions of cells can be isolated from the primary cell source. • Stemness retained after 30 replication cycles with their phenotype and karyotype intact |
Tumorigenicity | • Characteristically produce teratomas • Aneuploidy and accumulation of oncogenic mutations over multiple replication cycles produce aggressive teratocarcinomas | • MYC used in cell line generation is oncogenic • Cell line generation through viral vectors can activate integration site-adjacent oncogenes or suppress the tumor suppressor genes • Possible precursor adult cell epigenetic memory retention • Teratomas from undifferentiated cell contamination in the final product | • Genetically modified cells can generate teratomas through proto-oncogenic activation | • Highly proliferative but do not produce tumors • Acquiescent to transgene integration sans tumorigenesis |
Immunogenecity | In undifferentiated state: • Low immunogenicity • No expression of immunomodulatory molecules such as CD95 and IL-10 In differentiated state : • Immunogenicity is similar to adult fibroblasts • Mouse ESCs acquiescent to syngenic but not allogenic transplantations | Initially, T-cell-mediated autoimmune rejection observed in: • iPSC-derived myocardial, endothelial cells • Teratoma formation models Recently, successful allogenic transplantation of iPSC derived retinal pigment epithelial cells in immune-matched monkeys observed • Clinical study to observe iPSCs’ ability to arrest macular degeneration approved in Japan | • Long history of safety in clinical trials • Possible immunomodulatory properties Possible applications in: • Hematological malignancies and severe aplastic anemia • Autoimmune disorders | • Express MHC class I molecules HLA- A, B, and C as well as the non-classic HLA-G and -E • HLA-G and -E modulate maternal immune response, suppressing T cells, NK cells and dendritic cells • No expression of the co-stimulatory cell surface markers • Ideal for allogenic transplantation • Prolong co-transplanted cell survival |