Since the last time I wrote about stem cells, several things of note have occurred. Among these was the announcement that the Japanese researcher Haruko Obokata has resigned from the RIKEN Center for Developmental Biology, because the finding from her paper (Obokata et al. (2014)) – that she could induce a stem cell state by treating differentiated cells with acid – could not be reproduced. An investigation by the RIKEN Center has found that the supposedly reprogrammed cell cultures were likely contaminated by embryonic stem cell lines, but it is still unclear whether that was accidental or deliberate.
On a more positive note (assuming that these results are true), Irie et al. (2014) have been able to demonstrate the reprogramming of differentiated human epithelial cells into induced pluripotent stem cells (iPSC), which they then re-differentiated into primordial germ cells (PGC), the precursors of germ cells (egg and sperm cells). In particular, they found that the transcription factor SOX17 is a main regulator of this cell state in humans, whereas it is a different transcription factor, BLIMP1, in mice. The implications of this work are potentially vast (see the Nature blog comment here). For instance, when the PGCs generated from differentiated mouse cells were transplanted into mouse testes or ovaries they developed normally into sperm or egg cells, respectively, and were then amenable to in vitro fertilisation. Potentially, therefore, this recent advancement in human cells may be a step towards treating infertility, or enabling (male) homosexual couples to have their own biological children. However, there are biological, technical and ethical hurdles to be overcome if these findings are to be applied. The following figure summarises their findings and is copied directly from their graphical abstract:
The full text of Irie et al. can be viewed here as an open access text. And this is because the research and publication costs were covered by the Wellcome Trust, a “global charitable foundation dedicated to achieving extraordinary improvements in human and animal health”, which supports “public engagement, education and the application of research to improve health”. Many funding bodies, including the Wellcome Trust, are increasingly imposing the restriction that any of the research funded with their money must be published open access, including the sharing of raw data.
As one would say in German, I wish you “a good slip into the New Year”!
Irie N, Weinberger L, Tang WW, Kobayashi T, Viukov S, Manor YS, Dietmann S, Hanna JH, Surani MA (2014) SOX17 Is a Critical Specifier of Human Primordial Germ Cell Fate. Cell
Obokata H, Wakayama T, Sasai Y, Kojima K, Vacanti MP, Niwa H, Yamato M, Vacanti CA (2014) Stimulus-triggered fate conversion of somatic cells into pluripotency. Nature 505: 641-647