Induced pluripotent stem (iPS) cell technology demonstrates that somatic cells can be reprogrammed to a pluripotent state by over-expressing four reprogramming factors.This technology has created an interest in deriving iPS cells from domesticated animals such as pigs,sheep and cattle.Moloney murine leukemia retrovirus vectors have been widely used to generate and study mouse iPS cells.However,this retrovirus system infects only mouse and rat cells,which limits its use in establishing iPS cells from other mammals.In our study,we demonstrate a novel retrovirus strategy to efficiently generate porcine iPS cells from embryonic fibroblasts.We transfected four human reprogramming factors (Oct4,Sox2,Klf4 and Myc) into fibroblasts in one step by using a VSV-G envelope-coated pantropic retrovirus that was easily packaged by GP2-293 cells.We established six embryonic stem (ES)-like cell lines in human ES cell medium supplemented with bFGF.Colonies showed a similar morphology to human ES cells with a high nuclei-cytoplasm ratio and phase-bright flat colonies.Porcine iPS cells could form embryoid bodies in vitro and differentiate into the three germ layers in vivo by forming teratomas in immunodeficient mice.
RUAN WeiMinHAN JianYongLI PinCAO SuYingAN YangLIM BingLI Ning
Pluripotent stem cells(PSCs),including embryonic stem cells(ESCs)and induced PSCs(iPSCs),can differentiate into cells of the three germ layers,suggesting that PSCs have great potential for basic developmental biology research and wide applications for clinical medicine.Genuine ESCs and iPSCs have been derived from mice and rats,but not from livestock such as the pig-an ideal animal model for studying human disease and regenerative medicine due to similarities with human physiologic processes.Efforts to derive porcine ESCs and iPSCs have not yielded high-quality PSCs that can produce chimeras with germline transmission.Thus,exploration of the unique porcine gene regulation network of preimplantation embryonic development may permit optimization of in vitro culture systems for raising porcine PSCs.Here we summarize the recent progress in porcine PSC generation as well as the problems encountered during this progress and we depict prospects for generating porcine naive PSCs.
