An experiment in Japan succeeded for the first time in creating healthy, fertile mice that have two biological parents. Photo: referential/Salk Institute
At the beginning of March, a team of Japanese scientists announced an unprecedented achievement in the field of genetics: they created for the first time healthy mice whose both biological parents were male. Yes, as you read: the pups that were born did not carry the DNA of any female rodent, but only of two male specimens.
The experiment caused a lot of buzz in the scientific community because, unlike a similar experiment carried out in 2018 in which the resulting pups only lived for one day, these rodents were not only born healthy, but grew to be adults and reached have offspring normally.
Katsuhiko Hayashia geneticist at Osaka University and lead author of the research, began his study with the intention that one day this experimental procedure could help people with infertility to have children.
However, after the successful feat, Hayashi announced to the international press that “in a decade” the technology could be available for its application in humans, making it possible, for example, for two men to become the biological fathers of a baby. Will it be possible?
The main author of the research maintains that this experimental procedure tested in mice could be available for application in humans in the next decade. Photo: referential/AFP
converting male cells to egg cells
The experiment of artificial reproduction of these rodents began with cells extracted from the skin of two adult male mice, explain the Japanese scientists in their study, published in the Nature magazine.
These units were genetically reprogrammed in the laboratory so that they become a type of stem cells called induced pluripotent stem cells (iPS).
These cells are special when they come from a male mouse, since, when cultured for a long time, some of them tend to spontaneously lose their Y sex chromosomewhich determines the masculine gender in mammals.
Knowing this, Hayashi and his team selected stem cells lacking the Y chromosome; Subsequently, they expected another natural process —although also infrequent— that occurs in these structures after another long period of cultivation: the X chromosome duplication. In this way, they obtained stem cells with female sex chromosomes (XX).
Finally, these stem cells were genetically induced to become eggs capable of being fertilized.
After many attempts to fertilize the ovules inside an organoid that imitated the conditions of a rodent ovary, 630 embryos were obtained that were implanted in different females. Only seven of these animals gave rise to healthy offspring.
The feat was possible after creating an egg from male stem cells. Photo: ZEISS Microscopy/Flickr
Could it replicate in humans?
Despite the fact that this experiment is undoubtedly a great achievement in genetics, the truth is that its application in humans is still many years away from being investigated, say various scientists.
Lluis Montoliu, a biologist and researcher at the National Center for Biotechnology at the Autonomous University of Madrid, maintains that this procedure “is highly inefficient and is only technically possible in mice,” he writes in the scientific blog Naukas.
The main reason? The low chances of success at each stage of the process, be it when the stem cells lose the Y chromosome that determines the male sex, as well as during the successful fertilization of the eggs and the birth of a healthy offspring.
Meanwhile, for Amander Clark, a professor at the University of California (USA) who works with laboratory-grown gametes, transferring the work to human cells would be a “big leap”, since cultured human eggs have yet to be created. in the laboratory from female cells.