Scientists have successfully created mice with two biological fathers by creating eggs from male cells. The breakthrough could lead to therapies for severe kinds of infertility and the potential of same-sex couples having a biological child together. The research was led by Katsuhiko Hayashi at Kyushu University in Japan, who is considered a pioneer in the field of lab-grown eggs and sperm.
The procedure involves extracting a skin cell from the tails of male mice and developing it into a stem cell. Male mouse stem cells are then turned into female cells, and functioning egg cells are created by expanding them and treating them with medication. The eggs are ultimately fertilised and the embryos are put into female mice.
While a Chinese study in 2018 stated that mice with two mothers were born, the pups barely lived a few days when they tried it with male mice. However, the Japanese researchers took a different strategy, and the pups in their study appeared to grow normally and be capable of becoming parents in the conventional way.
Hayashi’s team is now seeking to reproduce this feat using human cells, but the adoption of lab-grown eggs for clinical purposes would face substantial challenges, including ensuring their safety. The approach might also be used to cure severe instances of infertility, such as women with Turner’s syndrome, in which one copy of the X chromosome is absent or partially missing, and that this was the primary objective for the research. However, translating the technology to human cells would be difficult as human cells must be cultured for significantly longer periods before they can create a mature egg, which increases the chance of cells accumulating undesirable genetic alterations.
