Scientists have created for the first time mice with two fathers by transforming male mouse stem cells into female cells in the laboratory.
That raises the remote possibility of doing the same for people, though experts caution that very few mouse embryos are born alive, and no one knows whether the same technique would work in human stem cells.
However, “It’s a very clever strategy that’s been developed to convert male stem cells into female stem cells,” said Diana Laird, a stem cell and reproduction expert at the University of California, San Francisco, who was not involved. in research. “It’s an important step for both stem cells and reproductive biology.”
The scientists described their work in a study published Wednesday in the journal Nature.
First, they took skin cells from the tails of male mice and turned them into ‘induced pluripotent stem cells’, which can develop into many different cell types or tissues. Then, through a process that involved growing them and treating them with a drug, they converted male mouse stem cells into female cells and produced functional egg cells. Eventually, they fertilized those eggs and implanted the embryos into female mice. About 1% of the embryos – 7 out of 630 – grew into live mouse pups.
The cubs appeared to be growing normally and were able to become parents themselves in the usual way, research leader Katsuhiko Hayashi of Kyushu University and Osaka University in Japan said last week at the third international summit. on human genome editing.
In a commentary published alongside the Nature study, Laird and his colleague, Jonathan Bayerl, said the work “breaks new ground in reproductive biology and fertility research” for animals and people. Down the road, for example, it may be possible to breed endangered mammals from a single male.
“And it could also provide a model for allowing more people,” such as male same-sex couples, “to have biological children, while sidestepping the ethical and legal issues of donor eggs,” they wrote.
But they raised several caveats. The most notable one? The technique is extremely inefficient. They said it’s not clear why only a small fraction of the embryos placed in the surrogate mice survived; the reasons could be technical or biological. They also stressed that it is still too early to know whether the protocol will work on human stem cells.
Laird also said scientists need to be aware of the mutations and errors that can be introduced into a culture dish before using stem cells to produce eggs.
The research is the latest to test new ways to create mouse embryos in the lab. Last summer, scientists in California and Israel created “synthetic” mouse embryos from stem cells without a father’s sperm or a mother’s egg or uterus. Those embryos mirrored natural mouse embryos up to 8.5 days after fertilization, containing the same structures, including one resembling a beating heart. The scientists said the venture could eventually lay the groundwork for creating synthetic human embryos for research in the future.
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