Researchers turn human skin cells into eggs — but not yet usable ones
[October 01, 2025]
By LAURAN NEERGAARD
WASHINGTON (AP) — Oregon scientists used human skin cells to create
fertilizable eggs, a step in the quest to develop lab-grown eggs or
sperm to one day help people conceive.
But the experiment resulted in abnormalities in the chromosomes,
prompting the Oregon Health & Science University team to caution it
could take a decade of additional research before such a technique might
be ready for trials in people.
The work published Tuesday in Nature Communications may offer lessons as
scientists try to learn to create eggs and sperm in a lab for the
infertile or to help same-sex couples have children genetically related
to both partners.
The OHSU team removed the nucleus from a human egg cell and replaced it
with the nucleus from a human skin cell. But a skin cell contains two
sets of chromosomes, and eggs and sperm are supposed to each contain
only one set that combine during fertilization. The researchers
therefore induced the egg-like cells to discard extra chromosomes,
injected donated sperm and jumpstarted post-fertilization development.
About 9% lasted for six days in lab dishes, reaching the blastocyst
stage of early embryo development, before the experiment was stopped.
The main problem: The chromosomes were abnormal in several ways.

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This undated image provided by the Mitalipov Laboratory at Oregon
Health & Science University shows a a microscope image of a human
egg that contains a nucleus taken from a skin cell. (Mitalipov
Laboratory via AP)
 “We kind of developed this new cell
division that can reduce chromosome number,” said study senior
author Shoukhrat Mitalipov, OHSU’s embryonic cell and gene therapy
director. “It’s still not good enough to make embryos or eggs
genetically normal.” He called the initial findings proof-of-concept
and said his team is working on improvements.
Scientists not involved in the work had mixed reactions. Columbia
University stem cell researcher Dietrich Egli was troubled by the
abnormalities.
But Dr. Eve Feinberg, who agreed that the chromosome problems were
critical, said it "seems like this team figured out how to reduce
the number, just not well yet. But it’s an important step and very
exciting.”
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