High-efficiency RNA-based reprogramming of human primary fibroblasts

Induced pluripotent stem cells (iPSCs) hold great promise for regenerative medicine; however, their potential clinical application is hampered by the low efficiency of somatic cell reprogramming. Here, we show that the reprogramming of human patient’s fibroblasts into iPSCs can be enhanced to an unprecedented efficiency via the synergistic activity of synthetic modified mRNAs encoding reprogramming factors and miRNAs-367/302s delivered as mature miRNA mimics. This synergism is dependent upon an optimal RNA transfection regimen and culturing conditions tailored specifically to primary human fibroblasts. As a result, we have developed a novel, integration- and feeder-free reprogramming approach that generates up to 4,019 TRA-1-60 positive colonies from only 500 starting human primary neonatal fibroblasts and reprograms up to 90.7% of individually plated cells, producing multiple sister colonies. This methodology consistently generates clinically relevant iPSCs from a variety of human patient’s fibroblasts and opens up new horizons for studying the biology of reprogramming.