Turning Skin Cells Into Viable Human Eggs Could be a Milestone in Treating Infertility
For some couples, even in vitro fertilization (IVF) cannot fulfill the desire for a biological child. Women who have undergone cancer treatment, those whose egg reserves have declined with age, and same-sex couples often face unique challenges that current fertility treatments cannot overcome.
Now, researchers at Oregon Health & Science University (OHSU) turned to human skin cells and successfully transformed them into viable eggs that can be fertilized.
“We achieved something that was thought to be impossible,” said senior author Shoukhrat Mitalipov, Ph.D., director of the OHSU Center for Embryonic Cell and Gene Therapy, in a news statement.
Their study, published in Nature Communications, has the potential to transform fertility treatments, but the researchers estimate it will take at least another decade to refine the technology.
Skin Cells to Human Eggs
The emerging field of in vitro gametogenesis, creating functional sperm and eggs from ordinary body cells, has long focused on reprogramming stem cells into gametes. However, this process is highly complex and can take months.
Instead, the OHSU team used somatic cell nuclear transfer (SCNT), a technique in which the nucleus of a skin cell can be placed into a donor egg. The idea is simple: shuttle genetic material into an egg that can then be fertilized. This principle was also used in the creation of the famous “dire wolf-like” Colossal wolves, born in 2024.
But there’s a catch. Because skin cells carry a full set of 46 chromosomes, the resulting egg nucleus would also carry a complete genome. That meant it couldn’t merge with another genome during fertilization to produce an embryo with contributions from both parents.
To understand the fix, it helps to revisit some cell biology basics.
Most body cells duplicate through mitosis, producing genetically identical copies with 46 chromosomes. Gametes (sperm and egg cells) work differently. Through meiosis, they reduce their chromosome count to 23, so when sperm and egg combine, the result is a full set of 46 chromosomes. That’s why we inherit half our DNA from each parent rather than becoming clones. Crucially, meiosis has always been considered unique to germ cells, not something a skin cell could pull off.
Read More: How Close Are We to Making Babies from Bone Marrow?
Creating a Viable Egg Cell
To solve the problem, the team developed a hybrid process they call “mitomeiosis,” which combines aspects of mitosis and meiosis.
Researchers at OHSU have demonstrated a new technique to treat infertility by turning skin cells into oocytes, or eggs. Shown here, an image of an oocyte with a bright image of a skin cell nucleus before fertilization.
(Image Courtesy of Oregon Health & Science University)
The key was timing. Researchers inserted the skin cell nucleus into a donor egg during metaphase, a critical stage of meiosis when chromosomes align at the cell’s center. They then applied a drug to push the cell through the rest of division.
The result: an egg carrying the normal half set of 23 chromosomes. Fertilized through standard IVF, it produced an embryo with a complete genome (46 chromosomes in total) containing genetic material from both parents.
A Promise With Limitations
While groundbreaking, the approach is far from ready for clinical use. The researchers created 82 functional oocytes (eggs prior to fertilization), but after fertilization with sperm, most embryos failed to progress past the early stages of development. Many displayed chromosomal abnormalities, known as aneuploidy, which commonly occur in human eggs and typically halt embryo development.
“Aneuploidy is pretty common in human eggs, especially with aging,” Mitalipov noted in the release.
The team emphasizes that their work is still proof of concept.
“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,” the authors wrote.
Ethical debates are sure to follow, and funding for long-term research isn’t guaranteed. Still, this work could mark a medical milestone, offering hope to those who currently have no path to a biological child.
Read More: My Long and Arduous Journey Across the Frontiers of Fertility Technology
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