In a landmark study, researchers have successfully created fertilizable human eggs using skin cells, a development that could pave the way for future infertility treatments. The findings, published in Nature Communications, represent a major scientific milestone, although experts caution that clinical use remains at least a decade away.
The study involved removing the nucleus from a donated human egg and replacing it with the nucleus from a skin cell, which carries most of a person’s genetic material. This process generated 82 immature human eggs that were then fertilized in the laboratory. The resulting eggs carried DNA from the donor of the skin cell and could be combined with sperm to form embryos.
According to Dr Paula Amato, coauthor of the study and professor of obstetrics and gynecology at Oregon Health and Science University, the research could one day help women who are unable to produce eggs, as well as same-sex couples who wish to have a child genetically related to both partners.
The researchers faced the challenge of correcting chromosome numbers, since skin cells contain 46 chromosomes while reproductive cells must carry only 23. By mimicking natural cell division, the team was able to discard the extra set, a process they termed “mitomeiosis.” Despite this innovation, fewer than 9% of the eggs developed into early-stage embryos, and all showed chromosomal abnormalities, making them unsuitable for producing healthy pregnancies.
Scientists emphasize that further work is needed to ensure accuracy and safety. Even in natural conception, only around one-third of embryos reach the blastocyst stage, the point where implantation typically occurs during IVF.
Experts not involved in the study welcomed the results with cautious optimism. Professor Amander Clark of UCLA described the work as an “important beginning” but noted that current limitations make the method unsuitable for clinical use. She highlighted the potential impact for women with ovarian insufficiency, for whom conventional IVF often fails.
The technique used in the study is based on somatic cell nuclear transfer, the same method employed to clone Dolly the sheep in 1997. While human reproductive cloning remains banned in many countries, the current research differs in that it combines genetic contributions from two parents rather than creating an identical copy of one.
Professor Ying Cheong of the University of Southampton called the results an exciting proof of concept. She noted that while the work is still in its early stages, it could eventually transform how medicine approaches infertility and miscarriage, and may open the door to creating egg or sperm-like cells for those without reproductive options.
