Scientists Create Mice With Two Fathers and No Mother: 'Revolutionary'

In a scientific milestone, baby mice have been born from eggs made out of male mouse cells, meaning that the offspring have two fathers and no mother.

Researchers from the Osaka University and Kyushu University in Japan described in a new study published in the journal Nature how they successfully changed male cells into eggs.

The researchers hope that their findings may pave the way for this technology's use in humans, allowing male couples to have biological children without using a female egg donor.

lab mouse preti dish
Stock image of a lab mouse in a petri dish. Scientists have figured out how to grow egg cells from male mouse cells, allowing two male mice to have biological offspring. iStock / Getty Images Plus

In the past, scientists have created mice with two biological fathers using genetic engineering and several complex steps using embryonic cells. They have also previously transformed female mouse body cells into eggs. This, however, marks the first time that viable eggs have been grown from male cells.

In the study, the scientists described how they took skin cells from a male's tail and cultured them in a petri dish to become pluripotent stem cells, which can grow to become any other cell type.

Like humans, male mice cells contain one X and one Y chromosome, while female cells contain two X chromosomes. During the culturing to become stem cells, roughly 6 percent of the mice cells lost their Y chromosome, leaving them as XO. The scientists then used a drug called reversine and a fluorescent protein to duplicate the existing X chromosomes, making the cells XX.

Next, the scientists manipulated the XX cells to grow into egg cells, which were then fertilized with the sperm of another male and implanted into a female mouse surrogate.

egg fertilization
Stock image of an egg being artificially fertilized. iStock / Getty Images Plus

Seven pups were born after 630 attempts, meaning that the success rate was around 1 percent. However, the pups themselves appear healthy and themselves are fertile, but will need to carefully study to investigate all and any ways in which they differ from those bred with a father and a mother.

This is a "revolutionary paper", Nitzan Gonen, the head of the sex determination laboratory at Israel's Bar-Ilan University, told AFP.

"This study provides insights that could ameliorate infertility caused by sex chromosome or autosomal disorders, and opens the possibility of bipaternal reproduction," the authors wrote in the paper.

However, this technology is a long way off being used in humans.

"There are big differences between a mouse and the human," Katsuhiko Hayashi, co-author of the study and professor of developmental biology at Osaka University in Japan said in a presentation at the Third International Summit on Human Genome Editing, held in London on March 8, per a report from Nature News. "I don't know whether this kind of technology can really adapt to human society."

Human gestation is 9 months compared to the 3 weeks it takes for a mice to give birth, meaning that a lot more could go wrong during the fetus's development. Additionally, the technology is very inefficient currently, with 99 percent of attempts failing.

Despite these challenges, Hayashi told The Guardian that he thinks it could be technologically possible in humans in as few as 10 years from now.

Another application of this finding could be recovering species from the brink of extinction if females are hard to come by.

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