Enhanced generation of iPSCs from older adult human cells by a synthetic five-factor self-replicative RNA

We previously devised a polycistronic, synthetic self-replicating RNA (srRNA) to generate human induced Pluripotent Stem Cells (iPSCs) that simultaneously expresses four reprogramming factors (4F). However, while the best 4F srRNA efficiently generated iPSCs from young fibroblasts, it was inefficient on adult human fibroblasts (>50 years). To increase the iPSC generation efficiency, we included additional reprogramming factors. We found that a single transfection of a five factor (5F) srRNA, containing OCT4, KLF4, SOX2, GLIS1 and c-MYC, robustly generated iPSCs from adult human fibroblasts aged 54 to 77 and from a 24 year old cardiomyopathy patient donor. Interestingly, 5F-srRNA induced LIN28A, which was one of the original reprogramming factors. 5F-srRNA also accelerated the generation of iPSCs by seven days compared to 4F-srRNAs. Further improvements include phosphatase treatment to remove 5' phosphate and use of Lipofectamine MessengerMAX that increased transfection efficiency to ~90%. Together, these improvements enabled us to efficiently generate iPSCs from human fibroblasts using 5F-srRNA while eliminating both puromycin selection and feeder cells.