Mice with ``both parents are male'' are born with eggs and sperm made from male cells

At the 3rd International Summit on Human Genome Mutation Editing, held in London on March 8, 2023, an initial proof-of-concept of a technology that could potentially be used to treat infertility was presented: By fertilizing it and then transplanting it into a female mouse, we succeeded in producing a mouse from between a male and a male.'

The mice with two dads: scientists create eggs from male cells


Mice have been born from eggs derived from male cells | New Scientist

Human cells with nuclear phase = 2n have 23 pairs of 46 chromosomes. One pair of these is a sex chromosome, and has a combination of XX in females and XY in males. And since eggs and sperm go through meiosis during their generation process, the nuclear phase becomes monophasic. In other words, the sex chromosome contained in the egg is always X, and the sex chromosome contained in the sperm is either X or Y. The sex of the offspring is determined by the sex chromosomes of the sperm.

Attempts to create embryos from males and males have been studied before, and 'researchers have been working on this feat for years,' said Keith Latham, a developmental biologist at the University of Michigan East Lansing. In 2018, it was

reported that using ES cells successfully produced puppies from two females or from two males. They grew and were fertile, but the puppies born to males lived only a few days.'

In 2020, Professor Katsuhiko Hayashi, who studies genome biology at the Graduate School of Medicine, Osaka University, started a project to create eggs using cells collected from adult male mice. Professor Hayashi and his colleagues created iPS cells by reprogramming cells taken from male mice. The culture was continued until some of the cells spontaneously lost the Y chromosome.

After that, they treated the cells with a compound called reversine , which promotes chromosomal instability, and searched for iPS cells with XX sex chromosomes, giving them the gene signals necessary for oocyte formation. The eggs formed in this way were fertilized with mouse sperm, and the embryos were transplanted into the uterus of female mice.

Of the 630 transplanted embryos, only seven grew into offspring mice, but the mice that grew up were fertile as adults, Hayashi reports. In the future, it is necessary to carefully observe the child mice obtained in this experiment and investigate whether there are any differences from the child mice born by the conventional method.

In particular, the question of how much of the epigenetic chemical decoration of DNA, which affects gene activity, is inherited in eggs derived from male cells is also expected in future research. Since epigenetics is an essential mechanism in important life phenomena such as ontogeny and cell differentiation processes, it is quite conceivable that changes in epigenetics lead to some abnormalities.

Professor Hayashi says that there are big differences between mice and humans, and it may not be possible to apply the same method to human cells as in this study. Michinori Saito, a collaborator and a developmental biologist at Kyoto University, said that using this research method to create eggs from human cells could take a considerable amount of time, and the culture period would be long. It points out that genetic abnormalities and changes in epigenetics accumulate.

by National Human Genome Research Institute

Tetsuya Ishii, a member of the Japanese Society for Bioethics and a professor at the Headquarters for Health and Safety at Hokkaido University, said, 'Professor Hayashi's research may lead to new areas of human reproduction. couples may be able to have biological children with the cooperation of surrogate mothers, or even one man may be able to have biological children.'

Professor Hayashi says, “The application of such research requires not only technical sophistication, but also a broader social debate about the ethics and implications of conducting it. I don't know yet if it can be applied to society.'

in Science, Posted by log1i_yk