In a major scientific achievement, Chinese researchers have successfully created the world's first mice with two fathers to reach adulthood. This breakthrough not only paves the way for new avenues in reproductive biology but also sheds light on a potential method to enhance embryonic development. The research team was led by Wei Li, a professor of genetic engineering at the Chinese Academy of Sciences (CAS) in Beijing.
Previously, scientists had successfully created mice with two mothers over 20 years ago, but achieving the same feat with two male parents had proven to be a significant challenge. The latest advancement was made possible through the precise genetic engineering of imprinted genes, which are typically expressed from only one parental copy, while the other copy is silenced, the South China Morning Post reported.
By using embryonic stem cell engineering, the researchers were able to reprogram the imprinted genes, effectively allowing the mice to develop with genetic material from two fathers
"We show that correcting 20 imprinted loci enables the development of viable bi-paternal mice,” the team led by scientists from the Chinese Academy of Sciences wrote in a paper published in the peer-reviewed journal Cell Stem Cell on Tuesday.
"These findings provide strong evidence that imprinting abnormalities are the main barrier to mammalian unisexual reproduction. This approach can significantly improve the developmental outcomes of embryonic stem cells and cloned animals, paving a promising path for the advancement of regenerative medicine,” Luo Guanzheng, co-corresponding author said in a journal press release.
Unlike certain species of lizards that can reproduce asexually, mammals have never been known to produce offspring without the involvement of two parents. Scientists have attempted to artificially induce single-parent reproduction in mammals for decades, but their efforts were initially met with limited success.
Further research revealed that the primary obstacle to single-parent reproduction in mammals was the presence of imprinted genes. Normally, mammals inherit one copy of each gene from each parent, and both copies can be expressed or only one is expressed through genomic imprinting. This process plays a vital role in development, and any disruptions to imprinting patterns can have severe consequences for the developing embryo.
"The unique characteristics of imprinting genes have led scientists to believe that they are a fundamental barrier to unisexual reproduction in mammals. Even when constructing bi-maternal or bi-paternal embryos artificially, they fail to develop properly and stall at some point during development due to these genes," explained Qi Zhou of CAS, a corresponding author of the study.
The challenge of overcoming the imprinting barrier has long hindered scientists' attempts to achieve single-parent reproduction in mammals. However, recent breakthroughs in genetic engineering have provided new avenues for exploring this complex phenomenon.
While the team's achievement is significant, they acknowledge that their research still has limitations. One major problem is the relatively low success rate of their approach, with only 11.8% of viable embryos developing to birth. Further, among those who were born, many did not survive to adulthood, and those who did often exhibited abnormal growth patterns and shorter lifespans.
The team's future research will likely focus on addressing these limitations and improving the overall viability and health of the offspring. They also intend to expand their research to larger animal models, such as monkeys, to test the feasibility and safety of their approach in more complex organisms.
