Epigenetic reprogramming--taking a lesson from the embryo.

Epigenetic reprogramming involves processes that lead to the erasure of epigenetic information. Such instances are typically connected with the reversal of differentiation and can potentially lead to the re-establishment of the pluripotent (embryonic stem (ES)-like) phenotype. Genome-wide epigenetic reprogramming occurs naturally in vivo in the course of normal mammalian development. Although in vitro reprogramming systems that can restore pluripotency in somatic cell have been designed, they are still very inefficient and the process requires considerably more time than the reprogramming processes that occur in vivo. Careful analysis of the developmental reprogramming events can give us mechanistic clues and enable us to design better in vitro experimental strategies.