Induced pluripotent reprogramming from promiscuous human sternness-related factors

Ectopic expression of pluripotency gene sets provokes nuclear reprogramming in permissive somatic tissue environments, generating nduced pluripotent stem (iPS) cells. The evolutionary conserved function of sternness orthologs was tested here through interspecies transduction. A spectrum of human immunodeficiency virus (HIV)-based lentiviral vectors was designed, and point mutations in the HIV-1 capsid region were identified for efficient infectivity and expanded transspecies tropism. Human pluripotent gene sequences, OCT3/4, SOX2, KLF4, and c-MYC, packaged into engineered lentiviral expression vectors achieved consistent expression in nonhuman fibroblasts. Despite variation in primary amino acid sequence between species, introduction of human pluripotent genes produced cell lines with embryonic stem cell-like morphology. Transduced fibroblasts differentiated in vitro into all three germ layers according to gastrulation gene expression profiles, and formed in vivo teratoma with multilineage potential. Reprogrammed progeny incorporated into nonhuman morula to produce blastomeres capable of developing into chimeric embryos with competent organogenesis. This model system establishes a prototypic approach to examine consequences of human sternness factors-induced reprogramming in the context of normal embryonic development by exploiting nonhuman early-stage embryos. Thus, ectopic xenotransduction across species unmasks the promiscuous nature of sternness induction, suggesting evolutionary selection of core processes for somatic tissue reprogramming.