A recent report in Nature (Lister et al.) has suggested that human induced pluripotent stem cells (iPSC), the great hope for personalised cellular therapy, are not as similar to embryonic stem cells (ESCs) as hoped, and that this may affect their use as a replacement for ESC in disease modelling and cellular therapy.
Centromeric and telomeric regions in iPSCs were found to maintain a DNA methylation state similar to that of their cell of origin, and were further linked to changes in methylation of histone H3 and transcriptional activity. Some regions of difference were shared between the multiple iPSC lines studied, suggesting that certain loci may be “inherently susceptible to aberrant methylation” while other regions of difference were iPSC specific, also suggesting “a stochastic element to reprogramming”. It was also observed that these differences are transmitted through differentiation of iPSC towards a trophoblastic lineage.