Virus-free induction of pluripotency and subsequent excision of reprogramming factors

This paper presents a technique to reprogram mouse and human fibroblasts to induce pluripotency. The authors show that the transgene can be removed once reprogramming has been achieved with a piggyBac transposon (described in an accompanying paper; doi:10.1038/nature07863). This system minimizes genome modification in induced pluripotent stem cells and enables complete elimination of exogenous reprogramming factors.