In a remarkable achievement, American scientists have created human eggs containing genes from adult skin cells, which could one day help infertile women or gay couples have babies with their own genes – but which would also raise difficult ethical, social and legal issues, reports NPR.
“It’s a significant step forward,” said Shoukhrat Mitalipov of the Oregon Health & Science University in Portland, who led the research, published in Nature Communications.
Millions of women can’t have children using their own eggs because of their age or other reasons. So scientists have been trying to create human eggs in the lab that carry the genes of people struggling to conceive.
The field is known as in vitro gametogenesis, and involves global researchers, including in Japan, as well as at US biotech companies.
“This technology would allow many of these women to genetically have their own eggs and to have a genetically-related child,” said Mitalipov.
He and his colleagues used a different technique from most other researchers pursuing this goal. The most common approach involves converting adult cells, such as skin or blood, into cells known as induced pluripotent stem, or iPS, cells.
Scientists have then tried to coax those iPS cells into becoming eggs or sperm. The closest anyone has come to success for eggs has been very primitive human egg cells that are too immature to be fertilised.
Mitalipov’s team instead borrowed the technique that was used to clone Dolly the sheep: they removed most of the DNA from a healthy donor egg and replaced it with most of the DNA from another woman’s skin cell.
Next, they essentially tricked the reconstituted egg to skip normal forms of cell division known as mitosis and meiosis. Instead, they coaxed the eggs to go through a different process they dubbed “mitomeiosis”. That produced 82 functional eggs, they reported.
The scientists then fertilised the eggs with sperm to see if they could develop into embryos. And it appears to have worked, at least in a small number of tries. Nine percent of the resulting embryos developed to the blastocyst stage, which is when embryos would be transferred into a woman’s womb, the researchers reported.
Tricky issues with a promising technology
However, none of the embryos would have been suitable to actually implant into a womb to develop further. That’s because all of them still had genetic abnormalities that would prevent healthy development.
But Mitalipov is hopeful he’ll eventually solve that problem. And other scientists are aggressively pursuing other approaches to accomplish the same goal.
Some other scientists praised the new research.
“I think it’s a very significant step in terms of moving forward to the ability to use skin cells to make egg cells for human reproduction at some point in the future, once we can prove this is safe and effective,” said Dr Sigal Klipstein, a reproductive endocrinologist with the American Society of Reproductive Medicine.
“The proof of concept is fascinating.”
If IVG is ever perfected, the technology could have applications beyond helping infertile women. IVG could, for example, also allow gay couples to have babies genetically related to both partners. Scientists could create eggs from a skin cell of one male partner and fertilise it with sperm from the other male partner.
“The implications are huge,” Mitalipov added.
But some scientists warn that the genetic abnormalities in Mitalipov’s embryos raise questions of whether this approach could ever work.
“It is unclear whether skipping meiosis in half the genome is compatible with human development,” said Amander Clark, a Professor of Molecular and Developmental Biology at the University of California-Los Angeles.
“Time and more fundamental research will tell.”
Ethical concerns abound
And even if it did work, the technology would create lots of tricky issues. Some worry this could help create “designer babies”, where parents can pick and choose the traits of their children.
“We could see more efforts to try to use it for so-called enhancement purposes – to try to get embryos that would be stronger or more athletic or more musical or better at math or more intelligent,’ said Hank Greely, a Stanford University bioethicist who wrote The End of Sex and the Future of Human Reproduction.
“Some people view that as a terrible prospect. Some people view that as a wonderful prospect.”
Another concern is that this could enable people to steal a skin cell from another person, like a celebrity, and make a baby with their DNA without their knowledge or permission.
“We could have Taylor Swift babies all over the world. It’s a theoretical possibility, but not crazy,” said Ronald Green, a Dartmouth College bioethicist. “It’s a technology that’s very promising. But it raises a number of daunting ethical questions.”
Another possibility is using this technology to create a “uni-baby”, a child containing only one person’s genetic material.
“That’s a very weird possibility,” Greely said. “Would anyone want to do that? Well, there are 8bn people in the world and some of them have very strong egos and some are very rich. So I wouldn’t guarantee that no one would want to do that.”
While all of those possibilities need to be debated, Greely and others argue that the technology is worth pursuing with proper oversight.
“If it were safe, it would offer relief to literally millions of people around the world who desperately want to have kids who are genetically theirs,” observed Greely.
Study details
Induction of experimental cell division to generate cells with reduced chromosome ploidy
Nuria Marti Gutierrez, Aleksei Mikhalchenko, Maria Shishimorova et al.
Published in Nature Communications on 30 September 2025
Abstract
Somatic cell nuclear transfer (SCNT) enables the direct reprogramming of somatic cells into functional oocytes, albeit with a diploid genome. To address ploidy reduction, we investigated an experimental reductive cell division process, termed mitomeiosis, wherein non-replicated (2n2c) somatic genomes are prematurely forced to divide following transplantation into the metaphase cytoplasm of enucleated human oocytes. However, despite fertilisation with sperm, SCNT oocytes remained arrested at the metaphase stage, indicating activation failure. Artificial activation using a selective cyclin-dependent kinase inhibitor successfully bypassed this arrest, inducing the segregation of somatic chromosomes into a zygotic pronucleus and a polar body. Comprehensive chromosome tracing via sequencing revealed that homologous chromosome segregation occurred randomly and without crossover recombination. Nonetheless, an average of 23 somatic chromosomes were retained within the zygote, demonstrating the feasibility of experimentally halving the diploid chromosome set. Fertilised human SCNT oocytes progressed through normal embryonic cell divisions, ultimately developing into embryos with integrated somatic and sperm-derived chromosomes. While our study demonstrates the potential of mitomeiosis for in vitro gametogenesis, at this stage it remains just a proof of concept and further research is required to ensure efficacy and safety before future clinical applications.
NPR article – Scientists create human eggs in the lab, using skin cells (Open access)
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