In a scientific milestone, baby mice were born from eggs made from male mouse cells, meaning the offspring have two fathers and no mother.
Researchers from Osaka University and Kyushu University in Japan described this in a new study published in the journal Nature how they successfully turned male cells into eggs.
The researchers hope their findings will pave the way for human application of this technology, allowing male couples to have biological children without using a female egg donor.
In the past, scientists have used genetic engineering and several complex steps to create mice with two biological fathers using embryonic cells. They have also previously converted female body cells from mice into eggs. However, this is 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 that can grow into any other cell type.
Like humans, male mouse cells contain an X and a Y chromosome, while female cells contain two X chromosomes. During cultivation into stem cells, about 6 percent of mouse cells lost their Y chromosome, leaving them as XO. The scientists then used a drug called reversin and a fluorescent protein to duplicate the existing X chromosomes and make the cells XX.
Next, the scientists manipulated the XX cells into growing into egg cells, which were then fertilized with sperm from another male and implanted into a female surrogate mouse.
After 630 attempts, seven puppies were born, meaning the success rate was around 1 percent. However, the puppies themselves appear to be healthy and self-fertile, but must be carefully examined to examine any and all ways in which they differ from those bred with a father and mother.
This is a “revolutionary paper,” Nitzan Gonen, head of the gender determination laboratory at Israel’s Bar Ilan University, told AFP.
“This study provides insights that could improve infertility caused by sex chromosome or autosomal disorders and opens up the possibility of bifamilial reproduction,” the authors write in the publication.
However, this technology is still a long way from being used in humans.
“There are big differences between a mouse and humans,” said Katsuhiko Hayashi, study co-author and professor of developmental biology at Osaka University in Japan, in a presentation at the Third International Summit on Human Genome Editing, held in London March 8, according to a report by Messages from nature. “I don’t know if this kind of technology can really adapt to human society.”
Human pregnancy lasts 9 months compared to the 3 weeks it takes for a mouse to give birth, meaning there could be a lot more that could go wrong during fetal development. In addition, the technology is currently very inefficient with 99 percent of attempts failing.
Despite these challenges, Hayashi told The guard that he believes it could be technologically possible in humans in just 10 years.
Another application of this finding could be to save species from extinction when females are hard to come by.
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