Japanese scientists have succeeded in creating femaleless mice. It will still take time before transposing this result to humans.

« This is the first case of making robust mammalian oocytes from male cells said Katsuhiko Hayashi at the third international summit on human genome editing, which took place on March 8 in London. This Japanese researcher and his team have achieved the feat of creating mice with two biological fathers. Their study is being reviewed for future publication.

Initially, the researchers took skin cells from male mice that were reprogrammed to behave like induced pluripotent stem cells (i.e. capable of differentiating into many cell types). The Y chromosomes of these cells have been replaced by X chromosomes, in order to obtain the “XX” combination specific to females. Then, fertilization of the synthesized eggs (in an ovarian organoid) with spermatozoa resulted in the creation of approximately 600 embryos. Implanted in carrier mice, these gave birth to seven mice, an efficiency of only 1%.

Transpose to humans to fight against infertility

This advance in reproduction could make it possible to fight against infertility in humans. For this, it will still be necessary to reproduce the operation in the laboratory using human cells, which is not planned for the moment. Some scientists believe that 10 or 20 years will suffice, while others suggest that it will be difficult to transpose the technique with the necessary security. In effect, ” human cells require much longer culture periods to produce a mature egg, which may increase the risk of cells acquiring unwanted genetic changes “, explain The Guardian.