defined cell of origin also allowed us to address the question of the degree of reprogramming achievable in iN cells. We particularly focused on how well the donor cell transcriptional program is silenced in resulting iN cells. Using both bulk and single cell transcription profiling methods we concluded that the donor cell program is efficiently silenced while low levels of some hepatic transcripts were still detectable in iN cells 3 weeks after the induction of the reprogramming factors. It may be likely that further optimization and extension of the culture period would result in even less expression or even extinction of this “epigenetic memory”.
