Mouse Eggs from Stem and iPS Cells

Okay, this is a big deal. A research team from Kyoto University has successfully used both murine stem cells and murine induced pluripotent stem cells to generate functioning oocytes. For those of you who do not excel in Latin, that means they took mouse embryonic stem cells and some ordinary mouse cells, and developed each into eggs. Those eggs were then used to create healthy mouse offspring.

This team and others have created both sperm and eggs from stem cells before, but haven't been able to produce healthy offspring from them. This time the researchers used proteins and other factors to induce the stem cells and iPS cells into becoming "primordial germ cell-like cells," or PGCLCs. The PGCLCs were then combined with cells from mouse ovaries to make artificial ovaries. These were then transplanted into female mice. After a month, the mice were found to be carrying immature eggs. The eggs were matured in vitro and then fertilized; the resultant embryos were transferred into female mice, who then gave birth. The happy mothers later became grandmothers, without need for further laboratory intervention.

Making oocytes out of stem cells would be impressive enough, but making them out of iPS cells is huge. This lab took an ordinary cell from a mouse, tweaked it and coaxed it into becoming an oocyte, and then made a baby mouse out of it. We're that much closer to being able to do that same trick for humans.

So, any tissue sample from any person, dead or alive, could in theory be used to make that person's baby. Did I say this was a big deal? Obviously it opens up some amazing possibilities for infertility treatment; but obviously, also, it poses huge challenges for control over the future uses of tissue in research and in the clinic.

The Meaning of Geron's Stem-Cell Decision

Michael Cook at BioEdge says the decision by Geron to end its human embryonic stem cell spinal-therapy research is a huge blow to those who believe in the therapeutic potential of hES cells. I have to disagree. It's true that the tissue-generating potential of hES cells was overblown in the battle to secure funding for hESC research. But I don't think Geron's move stands for anything greater than what it was: the decision of a single firm that its cancer research was more profitable than its stem-cell research. University-based work with hESCs and induced-pluripotent cells have shown real progress toward the tissue-generation goal; and, additionally, researchers are using stem cells as tools for drug-testing and for the analysis of diseased cells--work which is quite apt to have short-term therapeutic payoff.

Note, too, that while Geron had secured funding from the California Institute for Regenerative Medicine for its trial, it has given the money back with full interest, so there's no story here of wasting public funds.