Reprogramming somatic cells towards pluripotency by defined factors.

The recent years have seen great advances in reversal of programming of differentiated somatic cells towards pluripotency by methods not involving nuclear transfer. Some of these may present a first step on the way to individual-based cell therapy without the problems connected to collection of mammalian unfertilised oocytes. Although differentiation of cells involves complex genetic and epigenetic changes, it is now possible to generate cells with many properties of pluripotent embryonic stem cells by retroviral transduction of differentiated cells with only four transcription factors: Oct3/4, Sox2, Klf4 and c-Myc. The re-programmed cells contribute to live chimeric mice and are transmitted via the germline.