Using microRNAs to enhance the generation of induced pluripotent stem cells.

Somatic cells reprogrammed to acquire an ES-like state are termed iPS cells. In this unit, a protocol to use microRNAs as enhancers to increase the reprogramming efficiency is described. Mouse embryonic fibroblasts (MEFs) are isolated from E13.5 mouse embryos and seeded for reprogramming by defined factors. microRNA mimics are transfected into MEFs at two time points during this process to enhance the overall reprogramming efficiency. Two standard protocols for characterization of these miR-iPSCs, embryoid body formation and teratoma formation, are also provided. By using this method, the investigators can obtain a significantly higher number of bona-fide iPSC colonies and miR-iPSCs can be derived at a faster rate than with non-treated cells.