For the first time, mice born from two biological fathers have produced healthy offspring. This achievement relies on an unprecedented genetic manipulation, opening unexpected perspectives in reproductive biology.
Androgenesis, a natural phenomenon in some species, was until now considered impossible in mammals. However, a Chinese team has managed to overcome this obstacle by modifying key epigenetic mechanisms. This discovery sheds light on the limits imposed by evolution and the possibilities offered by genetic engineering.
Adult androgenetic mice.
Credit: Yanchang Wei The genomic imprinting barrier
In mammals, each parent transmits epigenetic marks regulating gene expression. These "imprints" differ depending on their maternal or paternal origin, preventing the development of embryos from a single sex. Researchers have identified seven critical regions where these marks need to be rebalanced to ensure viable offspring.
The team used CRISPR to modify these areas in sperm cells, mimicking the marks normally provided by the egg. The embryos obtained from two fathers were then implanted into surrogate mothers. Only 3 out of 259 embryos survived, with 2 reaching adulthood, and their subsequent fertility validates the principle.
This approach confirms the central role of genomic imprinting in embryonic development. The adult androgenetic mice showed normalized gene expression, unlike unmodified embryos that couldn't progress beyond early stages.
Applications and limitations
While the success rate remains low, this study proves that viable development is possible without maternal genetic contribution. Potential applications include preserving endangered species or assisting male couples. However, ethical and technical risks remain significant.
Researchers emphasize that parthenogenesis (embryos from two mothers) is much simpler to achieve. Androgenesis requires more challenging adjustments, reflecting different evolutionary constraints. These differences might explain its rarity in nature.
In the long term, this technique could improve fertility treatments or the study of genomic imprinting-related diseases. But its use in humans isn't conceivable for decades due to the risks and ethical questions raised.
Article author: Cédric DEPOND