Practice question

Induced pluripotent stem cells are engineered by ectopic expression of Yamanaka factors Oct4, Sox2, Klf4, c-Myc in somatic fibroblasts or blood cells, resetting epigenome to embryonic-like state. They self-renew indefinitely and differentiate into derivatives of three germ layers, useful for disease modeling and regenerative medicine without embryo destruction. Unlike embryonic stem cells isolated from blastocyst inner cell mass, iPSCs do not exist naturally in embryos; they require artificial reprogramming. They retain epigenetic memory and potential tumorigenicity, highlighting distinction between natural embryonic pluripotency and laboratory-induced pluripotency.