Researchers Challenge Reproductive Biology by Creating Human Egg from Skin Cell

Nature Communications, throw the foundations for a possible human reproduction without original oocytes. If the method is still at the experimental stage, it raises concrete perspectives for those who cannot use a classic in vitro fertilization.

Create an egg from a human skin cell: how does it work?

The heart of this feat is based on a technique called nuclear transfer of somatic cells (Somatic Cell Nuclear TransferSCNT). We know her for allowing the cloning of the Dolly sheep in 1996. Researchers from Oregon Health & Science University (OHSU) adapted this method to create functional human eggs from simple skin cells.

Concretely, the nucleus of a skin cell – containing the entire genetic heritage of the person – is extracted. It is transferred to a given oocyte whose nucleus has been previously removed. This new egg therefore contains the DNA of the skin cell, but with an initial chromosomal anomaly. It has 46 chromosomes, while a normal egg has 23.

To get around this problem, the team has developed an unprecedented procedure called Mitomeiosis, Mitosis and meiosis contraction. This step force the cell to simulate a meiotic type division and to eliminate half of its chromosomes. The objective is to obtain a haploid egg, capable of being fertilized like any natural egg.

The artificial stimulation of this division was made possible by the use of Roscovitine. It is an inhibitor targeting enzymes of cell cycle regulation, combined with electroporation. The latter consists of an electrical impulse making the cell membrane temporarily permeable to molecules. Once this step has been taken, the ovum thus modified is fertilized via intracytoplasmic injection of sperm (ICSI), IVF technique. This strategy does not seek to clone an individual, but rather to recreate an egg genetically linked to the donor person.

Encouraging results, but still very limited

Despite the spectacular nature of success, the results obtained show the major technical limits of the current method. Of the 82 artificial eggs generated, only 9 % reached the blastocyst stage. Or the sixth day after fertilization. At this stage, embryos are generally ready to be established in a uterus during IVF.

But all the embryos obtained had a major anomaly: defects of chromosomal segregation. This means that the chromosomes had not been properly distributed between the artificial egg and the structures supposed to evacuate the genetic excess (polar bodies). Result: aneuploid embryos, with an incorrect number of chromosomes or poorly constituted pairs.

This anomaly is unacceptable. It prevents any long -term viable development. Paula Amato, co -author of the study, stresses that this anomaly remains for the moment a major obstacle. Without a set of 23 functional chromosomes, the embryo is non -viable. The absence of genetic recombination between chromosomes, usually present in natural meiosis, further worsens the situation.

In comparison, even embryos from natural reproduction have only a success rate of 30 to 40 % to reach this same stage. The low rate observed here is therefore not completely extraordinary. However, it reflects an effectiveness that is still too low to consider clinical application.

The team continues their work to try to control the chromosomal distribution more precisely and reduce the error rate. According to Live Science, Nuria Marti-Gotierrez, first author, insists on the need to better understand the mechanisms of alignment and separation of chromosomes to make this process make this process more.

Towards a reproduction extended to audiences excluded from IVF

If the technique were to be mastered, its implications would far exceed the framework of basic research. It could radically transform the prospects for biological reproduction for audiences currently excluded from conventional treatments, such as fertilization in vitro (IVF).

Among the main targets are women whose ovaries no longer produce oocytes, due to age or medical treatment such as chemotherapy. Today, these women have no choice but to use ovules of donors, excluding any genetic link with the child.

With this new approach, it would be theoretically possible to create an egg from a cell of their skin, thus restoring this direct genetic filiation. Even more surprising, the technique could concern men. Nothing prohibits using male skin cells to create eggs, which would then be fertilized with the sperm of a partner.

“” This opens the possibility, in the long term, for male homosexual couples to have a child genetically from the two parents “Summarizes Paula Amato to Guardian. However, this scenario poses additional biological challenges. In particular linked to the parental genomic imprint, which differs according to the original sex of cells.

The researchers insist: no clinical application is envisaged immediately. It would take at least a decade to reach technological maturity.

Major ethical and scientific issues to anticipate

Beyond biomedical promises, this type of research raises many ethical and regulatory questions. They must imperatively be debated before any clinical application. By creating gametes from somatic cells, scientists redefine the biological limits of human reproduction.

The transition from a skin cell to an egg capable of fertilization blurs the distinctions between reproductive and non -reproductive cells. As Evie Kendal, bioethician at the University of Swinburne, points out by ABCthis places research in a legal vagueness. In Australia, for example, creating an embryo from a skin cell could be considered illegal, according to the way in which the law interprets the purpose of the cell.

Another major issue: transparency and scientific governance. For Roger Sturmey, specialist in reproductive medicine at the University of Hull, this research impresses with its rigor. But she demands ” Robust governance to guarantee social acceptability and public confidence ».

In addition, the safety of the embryos produced is far from guaranteed. The absence of genetic recombination, frequent aneuploidism, or even uncertainties linked to the epigenetic reprogramming of somatic cells remain as many major risks for the health of future children.

Finally, the ethical debate must also relate to the concept of genetic parenting shared between two people of the same sex. A totally unprecedented perspective in the history of human reproduction. The current legislative framework is not prepared for these transformations. A collective reflection, involving researchers, lawyers, health professionals and citizens, now seems essential.

Source: Marti Gutierrez, N., Mikhalchenko, A., Shishimorova, M. et al. “Induction of Experimental Cell Division to Generate Cells with reduced chromosome ploidy”. Common nat 168340 (2025).