Katsuhiko Hayashi is a pioneer in the field of laboratory-grown sperm and eggs at Kyushu University in Japan. The data was brought forward during an International Summit on Human Genome Editing at the Francis Crick Institute in London where he said it is technically possible to create a viable human egg cell from a male skin cell within a decade. And all of them without needing female cells. Now they have just been and published in the scientific journal «Nature»
Hayashi presented during this event the first mice born from two biological parents by generating eggs from male cells, and which raises an intriguing possibility for reproduction: that male partners have their own children The research, still in its early stages , involved converting the male XY sex chromosomes to female XX.
Speaking to the BBC, Professor George Daley from Harvard Medical School, who is not involved in the research, said there was still a long way to go before society was faced with such a decision. “Hayashi’s work is unprecedented but fascinating. [Hacer esto en humanos] it is more difficult than the mouse -he warned-. We still don’t understand enough about the unique biology of human gametogenesis (the formation of reproductive cells) to replicate Hayashi’s provocative work in mice.”
Hayashi explained that the work was at a very early stage, and that the eggs were of low quality and the technique could not be used safely in humans at this stage.
In a sense, Antonio Requena, medical director of the Valencian Infertility Institute (IVI) tells ABC Salud that this research “joins others that are being carried out in the field of the use of adult cells that are transformed into stem cells to later be able to develop them into the type of cells you are looking for.”
This, he says, “has already been proven in the development of other types of tissues, but I think its transformation into oocytes is difficult due to the complexity of the oocytes (not only because of the transmission of chromosomes, but because of the complexity of the cytoplasm that will be the support of the future embryo in the first days of development). In fact, there are already publications on the production of mouse spermatozoa from undifferentiated adult cells, but I find that this technique is easier (within its complexity) since the spermatozoon’s main function is only to provide the genetic load. of the male.”
The technique in question involves first taking a skin cell from a male mouse and then turning it into a stem cell, a cell that can develop into other types of cells.
The cells are male and therefore have XY chromosomes. Professor Katsuhiko’s team deleted the Y chromosome, duplicated the X chromosome, and then spliced the two Xs together. This adjustment allows the stem cell to be programmed to become an egg.
Cromosoma X
Treatment of the cells with reversin, a drug that interferes with cell division, increased the efficiency of X chromosome duplication. The resulting cells with two X chromosomes were induced to differentiate into primordial germ cells and then ova, which, when were fertilized and implanted in the uterus of a mouse, they produced viable offspring. About 1% of the implanted embryos gave rise to pups (7 out of 630).
Male and female gametes, sperm and oocytes (eggs), respectively, are produced from a type of stem cell called primordial germ cell, Hayashi explains in the Nature article. But the differentiation of these stem cells into gametes requires the proper functioning of the sex chromosomes. Yo
Previous research investigating the possibility of altering the sex of primordial germ cells found that gamete production was decreased or produced cells with low fertility.
What Hayashi’s team now asserts is that the use of pluripotent stem cells (including embryonic stem cells and induced pluripotent stem cells) could have the potential to produce more robust eggs.
The technique could be used to help infertile couples where the women are unable to produce their own eggs.
Antonio Requena
Medical Director of the Valencian Infertility Institute
The technique could be used to help infertile couples where the women are unable to produce their own eggs. However, she stressed that it was a long way from being available as a fertility treatment.
“Even in mice there are many problems with the quality of the egg. Before we can think of it as a fertility treatment, we have to overcome these issues.”
However, this scientific advance raises ethical problems. For example, Hayashi stressed that he would not be in favor of a man using it to create a baby using his own artificially created sperm and eggs.
“Technically this is possible, but I’m not so sure if it’s acceptable to society.”
However, he acknowledged to BBC News that the current problems could be resolved in ten years and that it could become an infertility treatment for both men and women, but also for same-sex couples if its safety is proven.
Its application in humans is, for Requena, «something hypothetical»and in any case, he explains «we would talk about a genetically derived offspring from two males, but that would need a surrogate maternal uterus for fetal development».
“If people want it and if society accepts that technology, then yes, I’m for it.”
Professor Amander Clark, from the University of California, Los Angeles, said the LBGTQ+ community should have a say in the use of technology for reproduction.
“The LGBTQ+ community has unique needs when it comes to having a family. It is possible that in the future same-sex reproduction will be based on current research using laboratory models to develop the technology.”
For the director of the IV, in the future it will be possible to produce gametes in humans through the “dedifferentiation of adult cells”, but I think that there is still a long way to go to reach this point. “The day it is achieved will be of great help to couples who today need a donation of gametes (ovules, semen or both) to achieve a pregnancy.”
Requena concludes that “this could be a reality in humans, it could be possible, but we think there is still a long way to go.”