| Sep 30, 2025 |
Human eggs made from skin cells can be fertilized
Early lab work shows reprogrammed skin cells can yield embryos, hinting at future infertility solutions but raising safety questions that demand more study.
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(Nanowerk News) In a striking proof-of-concept study, researchers have shown that human skin cells can be coaxed into becoming fertilizable eggs. The work, published in Nature Communications ("Induction of experimental cell division to generate cells with reduced chromosome ploidy"), demonstrates a possible route toward addressing infertility, though scientists stress the technique is still at an early stage and far from clinical use.
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Infertility affects millions of people worldwide, often because one of the two gametes required to form an embryo—the sperm or the egg—is absent or dysfunctional. For those who cannot rely on their own eggs, conventional in vitro fertilization (IVF) offers little help. A longstanding idea in reproductive biology has been to generate eggs from a patient’s own cells, but the barriers have been formidable.
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The approach used by Shoukhrat Mitapilov and his colleagues builds on somatic cell nuclear transfer, a process in which the nucleus of a patient’s body cell is placed inside a donor egg cell that has had its nucleus removed. The challenge with this method is that the resulting cell contains two full sets of chromosomes instead of one, which would lead to embryos with an extra set of genetic material.
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To overcome this, the team developed a new process they call “mitomeiosis.” By mimicking the reduction division that occurs naturally when eggs or sperm are formed, mitomeiosis forces the transplanted nucleus to discard one set of chromosomes.
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| Microscope image of a human egg cell during nuclear transfer. Researchers inserted genetic material from skin cells into donor eggs, a step toward generating functional oocytes. (Image: Mitalipov laboratory)
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“For the first time, scientists have shown that DNA from ordinary body cells can be placed into an egg, activated, and made to halve its chromosomes,” said Ying Cheong, a professor of reproductive medicine at the University of Southampton. “This breakthrough, called mitomeiosis, is an exciting proof of concept.”
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Using this method, the team was able to generate 82 functional oocytes, which were then fertilized with sperm in the laboratory. Roughly 9% of these fertilized eggs developed into blastocysts—the ball of cells formed about six days after fertilization, just before implantation would normally occur in IVF. None were grown beyond that point.
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Despite this progress, the hurdles remain significant. Many embryos did not develop at all, and those that reached the blastocyst stage often carried chromosomal abnormalities.
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Richard Anderson, professor of clinical reproductive science at the University of Edinburgh, emphasized both the promise and the caution: “The ability to generate new eggs would be a major advance, and this study shows that the genetic material from skin cells can be used to generate an egg-like cell with the right number of chromosomes to be fertilised and develop into an early embryo. There will be very important safety concerns but this study is a step towards helping many women have their own genetic children.”
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Other experts note that beyond the technical issues, the ethical dimensions of creating human eggs in the laboratory will require careful oversight and public engagement. Roger Sturmey, professor of reproductive medicine at the University of Hull, remarked: “This insightful piece of research demonstrates that the chromosomes of a differentiated adult cell can be persuaded to undergo a specific kind of nuclear division that would normally be seen only in eggs or in sperm. This is important, because it opens up the possibility of creating functional new egg cells… However, the rates of success reported in the study are comparatively low, and so the prospect of putting all this to clinical use remains distant.”
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While mitomeiosis is still a laboratory curiosity, it represents a step toward in vitro gametogenesis—the ability to generate gametes from non-reproductive cells. Cheong summed up the broader vision: “In practice, clinicians are seeing more and more people who cannot use their own eggs, often because of age or medical conditions. While this is still very early laboratory work, in the future it could transform how we understand infertility and miscarriage, and perhaps one day open the door to creating egg- or sperm-like cells for those who have no other options.”
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