This photo provided by researcher Katsuhiko Hayashi shows stem cell-derived mice, four weeks after their birth, in Osaka, Japan in September 2021. In a study published Wednesday, March 16, 2023, in the journal Nature, scientists led by Hayashi have created mice with two fathers for the first time by transforming male mouse stem cells into female cells in a laboratory. | Photo credit: AP
For the first time, scientists have created baby mice from two males.
That raises the remote possibility of using the same technique for people, though experts caution that very few mouse embryos have developed into live mouse pups, and no one knows if it would work for humans.
Still, “It’s a very clever strategy,” said Diana Laird, a stem cell and reproduction expert at the University of California, San Francisco, who was not involved in the research. “It is an important step in both stem cell and reproductive biology.”
The scientists described their work in a study published Wednesday in the magazine 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 types of cells 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 comment posted 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 donated 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 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 such as a beating heart. The scientists said the venture could eventually lay the groundwork for creating synthetic human embryos for research in the future.