US researchers say they have, for the first time, succeeded in turning human skin cells into fertilizable eggs. As the scientists announced on Tuesday in the journal Nature Communications, they used human DNA in the lab rather than mouse DNA. If successful, the in vitro gametogenesis (IVG) procedure could help infertile or older women have children of their own.
The method could also allow same-sex couples to “have a child genetically related to both partners,” said co-author Paula Amato of Oregon Health & Science University to the AFP news agency.
The method had previously been successful in mice
So far, the approach had only been tested in mice: In July, a research team from Japan announced that they had used this method to breed mice with two biological fathers.
The human-DNA study now represents a significant advance, but the researchers acknowledge that the technique is still years away from being available to prospective parents. The biggest hurdle, according to Amato, is to obtain eggs that are genetically normal with the correct number of chromosomes and the proper arrangement of those chromosomes.
For their study, the scientists first removed the nucleus from ordinary skin cells and then transferred it into a donor egg whose nucleus had been removed. This technique, also known as somatic cell nuclear transfer, was used in 1996 to clone Dolly the sheep.
The experiment was halted
However, one problem remained: skin cells carry 46 chromosomes, while eggs carry 23. The researchers managed to remove the extra chromosomes using a special process that mimics normal cell division.
They ultimately produced 82 developing eggs, which were then fertilized with sperm through in vitro fertilization (IVF). After six days, fewer than nine percent of the embryos had progressed enough to be considered for transfer to a uterus. The embryos displayed a number of abnormalities, and the experiment was terminated.
A door to the creation of eggs or sperm opened
The British researcher Ying Cheong praised the study as a “highly interesting” breakthrough. For the first time, scientists had shown “that DNA from ordinary body cells can be inserted into an egg, activated, and caused it to halve its chromosomes,” said the reproductive medicine specialist from the University of Southampton. She noted that the steps mirror the processes that normally lead to the formation of eggs and sperm.
Even though the work remains “very early” laboratory research, the studies could in the future “transform our understanding of infertility and miscarriages and perhaps one day open the door to creating eggs or sperm‑like cells for people who have few other options.”
