This account is by Teisha Rowland, a student at UC Santa Barbara who uses hESCs and iPSCs. She runs a blog called allthingsstemcell.com
Physiological differences have not been reported between embryonic stem cells and induced pluripotent stem cells, but new work shows consistent gene expression differences between them. One of the biggest questions in the field has been how similar these cells really are. If there are differences, are those due to suboptimal techniques for making iPS cells, or the fact that iPS cells don’t come from an embryo?
At ISSCR in Barcelona, Kathrin Plath of UCLA reported that there are some distinct gene and miRNA expression differences between them. She compared four iPSC lines made using different methods and found that 15 genes that are consistently expressed in these lines have significantly different expression levels in ESCs. In particular, basic cellular processes are down-regulated in iPSCs compared to ESCs, while regulation of genes involved in differentiation is up-regulated. Plath suggests that this may be because the fibroblasts from which the iPSCs are made aren’t sufficiently reprogrammed. Interestingly, late-passage iPSC gene and miRNA expression more closely resemble the ESC profile than the early-passage iPSC does, in Plath’s analysis. Plath hypothesizes that this may be caused by selecting iPS cells that most resemble ESCs over many passages. Ultimately, Plath suggests that iPSCs should be thought of as a different type of pluripotent stem cell, distinct from ESCs.
See also Plath’s recent publication in Cell Stem Cell
Session and write-up info
Speaker: Kathrin Plath
Talk title: Mechanisms of Transcription Factor-Induced Reprogramming
(Thursday, Concurrent Session I, Track A)
Note from Niche editor This post comes as a response to my solicitation in June calling for people to submit their accounts of ISSCR 2009. I’d asked people to describe what most interested them and to disclose any conflicts of interest. I’m very grateful for these volunteers’ help making more information available.