In a world first, scientists in Japan have created a baby mouse with two fathers. Instead of using an egg cell from a female, they were able to take a skin cell from one of the male mice and convert it into an egg. They then fertilized this with a sperm cell from the other male.
The research points toward the possibility of radical new treatments for infertile couples. It also suggests that someday in the future, a male couple could have a biological child together using a mixture of just their own DNA, and not a surrogate egg donor.
A surrogate would still need to carry the child.
“This is the first case of making robust mammal oocytes from male cells,” said Katsuhiko Hayashi, who led the work at Kyushu University in Japan.
Hayashi presented the results at the Third International Summit on Human Genome Editing at the Francis Crick Institute in London yesterday.
“Purely in terms of technology, it will be possible [in humans] even in 10 years,” said Hayashi. He indicated he would be happy for gay men to make use of the procedure if it was shown to be safe in humans.
However, he recognized there were bigger ethical implications.
“I don’t know whether they’ll be available for reproduction,” he said. “That is not a question just for the scientific program, but also for [society].”
“Significant potential applications”
The research was partly driven to see if fertility was possible for women who have Turner Syndrome. The genetic disorder is carried only on female chromosomes.
Other scientists described Hayashi’s 10-year prediction as wildly optimistic. It’s not been possible to convert a human female cell into a lab-grown egg as yet, let alone a male cell.
“We still don’t understand enough of the unique biology of human gametogenesis to reproduce Hayashi’s provocative work in mice,” Prof George Daley, the dean of Harvard Medical School, told The Guardian.
Despite this, news of the research has prompted interest around the world.
“This is a significant advance with significant potential applications,” Keith Latham, a developmental biologist at Michigan State University in East Lansing, told Nature.
Although presented at yesterday’s seminar, Hayashi’s work has yet to be submitted to a journal for peer review.
How they managed it
The work saw the male skin cells reprogrammed into a stem cell-like state. Female cells have XX chromosome pairings. Males have XY. In this case, the male Y-chromosome was removed and replaced with an X-chromosome from another cell. The cell then had the XX chromosome pairing.
The cells were cultivated in a culture system designed to replicate the conditions inside a mouse ovary.
The team was able to produce 600 embryos using this method. This resulted in the birth of seven mouse pups. That’s around a 1% success rate.
The mice appeared to grow as normal. As adults, they went on to father children of their own and live a normal lifespan.