Prolonged culture of embryos, stem cells and more Free Stuff

This week's (June 27) Nature.com "Advance Online Publication" contains two "Letters" describing the production of embryonic stem cells from "epiblast" cells, one in mice and rats, one focusing on mice.

Full content is restricted to subscription-only, but you can listen to a discussion about the studies on the free podcast from Nature, here, and the first paragraph of each is available for free, here and here. I believe you can also download the pdf of the Supplementary material for the articles here and here. You can find old podcasts and the English transcripts of previous podcasts, here.

One point that I find interesting is the statement on the Podcast that "what we thought were mouse eS Cells (embryonic stem cells), probably weren't." The second is that, beyond the obvious concerns about increased interest in growing human embryos to a later stage, this research was carried out in human embryos before moving on to mice and rats. From the first reference:

We initially determined that prolonged culture of human ES cells in chemically defined medium (CDM) containing activin A and FGF2 (CDM/AF) maintained their fundamental characteristics (See Supplementary Data). We then tested similar conditions for derivation of pluripotent cells from pre- and post-implantation rodent embryos.

The good news is that the scientists are convinced that these "EpiSC's" - or Epiblast stem cells - will be useful as models for the study of embryonic development and substitute for the human embryonic stem cells, without the limits on US Federal funding. (I'm always fascinated by the interest that British publications have in our US funding schemes and politics.)

If I'm correct in interpreting the importance of this information, scientists should find it easier to do experiments that they've been wanting to do by using rodent embryonic stem cells, now that they know how to find the actual cells, themselves. We will also hear more advocacy for the "culture" of human embryos longer than the previous 3 to 5 days, in order to harvest truly pluripotent eSC's, from what one article calls the "embryo proper" or the body of the would-have-been-born individual. One researcher tells us on the Podcast that these cells from embryos at the stage when the embryo would naturally implant are the "universal stem cells" that scientists have been searching for.