Generation of induced pluripotent stem cells using chemical inhibition and three transcription factors.

Generation of induced pluripotent stem (iPS) cells from differentiated cells has traditionally been performed by overexpressing four transcription factors: Oct4, Sox2, Klf4, and c-Myc. However, inclusion of c-Myc in the reprogramming cocktail can lead to expansion of transformed cells that are not fully reprogrammed, and studies have demonstrated that c-Myc reactivation increases tumorigenicity in chimeras and progeny mice. Moreover, chemical inhibition of Wnt signaling has been shown to enhance reprogramming efficiency. Here, we describe a modified protocol for generating iPS cells from murine fibroblasts using chemical inhibition and overexpression of three transcription factors. Using this protocol, we observed robust conversion to iPS cells while maintaining minimal contamination of partially reprogrammed transformed colonies.