In a groundbreaking scientific achievement, researchers in China have successfully created mice with two biological fathers that have reached adulthood. This remarkable feat, published in the journal Cell Stem Cell, signifies a major leap in reproductive biology and genetic engineering. Traditionally, mammalian reproduction requires genetic material from both a male and a female due to complex imprinting processes that silence certain genes depending on parental origin.
The team, led by Professor Wei Li at the Chinese Academy of Sciences, overcame this fundamental biological barrier through precise genetic modifications. They focused on “imprinted genes,” which are crucial for proper embryonic development and are normally expressed from only one parent. By making specific edits to 20 such genes in male haploid embryonic stem cells, they effectively mimicked the necessary maternal genetic contribution.
This intricate process involved injecting modified stem cells along with sperm from a second male into an egg cell from which the nucleus (and thus the female genetic material) had been removed. The resulting embryos, carrying genetic material exclusively from two male parents, were then implanted into surrogate female mice. This method represents a significant advancement over previous attempts, which often resulted in embryos failing to develop properly or pups dying shortly after birth.
While the success rate of this technique was low, with only a small percentage of embryos developing to term, the fact that some of these “bi-paternal” mice survived to adulthood is a monumental first. This breakthrough provides invaluable insights into the complex mechanisms of mammalian reproduction and the role of genomic imprinting in development. It offers a deeper understanding of why unisexual reproduction is naturally impossible in mammals.
However, the adult bi-paternal mice did exhibit certain limitations, including abnormal growth patterns, shorter lifespans, and, crucially, infertility. Despite these challenges, the research opens up new avenues for understanding and potentially addressing reproductive disorders, as well as advancing the field of regenerative medicine. The insights gained from manipulating imprinted genes could have far-reaching implications for future genetic engineering and therapeutic cloning.