Two men may be able to have biological children together in the future

A stunning scientific experiment
Same-sex couples could have biological children together
First made mammal eggs with male cells
International Summit on Human Genome Editing
Possible within a decade?
Viable lab-grown human female eggs haven’t yet been created
Transforming skin cells
Male skin cells reprogrammed
Y chromosome replaced by an X chromosome
The biggest trick: to duplicate the X chromosome
Cells cultivated in an ovary organoid
600 embryos resulted in seven mice
The mice lived healthy lives
Replicating the achievement with human cells
Safety concerns
A question for society
Technique also applied to treat severe infertility
Turner’s syndrome
Risk of acquiring unwanted genetic changes
Precursors of lab-grown human eggs
An engineering challenge
A stunning scientific experiment

In March 2023, at the Third International Summit on Human Genome Editing at the Francis Crick Institute in London, a Japanese scientist presented a stunning creation: mice with two biological fathers, an advance that opens up new possibilities for human reproduction.

Same-sex couples could have biological children together

The prospect of same-sex couples being able to have a biological child together in the future, was in everyone’s mouth at the Human Genome Editing Summit, according to The Guardian.

First made mammal eggs with male cells

This is the first case of making robust mammal oocytes from male cells, according to Katsuhiko Hayashi, who led the work at Kyushu University in Japan.

International Summit on Human Genome Editing
Hayashi, internationally renowned as a pioneer in the field of lab-grown eggs and sperm, published his research in the journal Nature and presented it at the scientific event, several media reported.
Possible within a decade?
Katsuhiko also predicted that it will be technically possible to create a viable human egg from a male skin cell within a decade.
Viable lab-grown human female eggs haven’t yet been created
However, other scientists suggested this timeline was optimistic given that they are yet to create viable lab-grown human eggs from female cells.
Transforming skin cells

The study relied on a sequence of intricate steps to transform a skin cell, carrying the male XY chromosome combination, into an egg, with the female XX version, the research showed.

Male skin cells reprogrammed

Male skin cells were reprogrammed into a stem cell-like state to create so-called induced pluripotent stem (iPS) cells.

Photo: CDC/Unsplash

Y chromosome replaced by an X chromosome

The Y-chromosome of these cells was then deleted and replaced by an X chromosome “borrowed” from another cell to produce iPS cells with two identical X chromosomes.

The biggest trick: to duplicate the X chromosome

“The trick of this, the biggest trick, is the duplication of the X chromosome,” Hayashi told The Guardian. “We really tried to establish a system to duplicate the X chromosome.”

Cells cultivated in an ovary organoid

Finally, the cells were cultivated in an ovary organoid, a culture system designed to replicate the conditions inside a mouse ovary, according to the research published in Nature.

600 embryos resulted in seven mice

When the eggs were fertilised with normal sperm, the scientists obtained about 600 embryos, which were implanted into surrogate mice, resulting in the birth of seven mice.

The mice lived healthy lives

The mice appeared healthy, had a normal lifespan, and went on to have offspring as adults, said Hayashi, according to The Guardian.

Replicating the achievement with human cells

Hayashi’s team is now attempting to replicate thachievement with human cells, although there would be significant hurdles for the use of lab-grown eggs for clinical purposes.

Safety concerns
“Purely in terms of technology”, it would be possible to create a human egg from male skin cells, Hiyashi told The Guardian. But they have yet to establish how safe it would be.
A question for society
Furthermore, “it is not a question just for the scientific programme, but also for society,” added the scientist.
Technique also applied to treat severe infertility

The technique could also be applied to treat severe forms of infertility, including women with Turner’s syndrome, according to Hayashi.

Turner’s syndrome
In Tuner’s syndrome, one copy of the X chromosome is missing or partly missing. In Nature, Hayashi said this application was the primary motivation for the research.
Risk of acquiring unwanted genetic changes

However, some scientists suggested that human cells require much longer periods of cultivation to produce a mature egg, which can increase the risk of cells acquiring unwanted genetic changes.

Precursors of lab-grown human eggs

Scientists have already created the precursors of human eggs, but until now the cells have stopped developing before the point of meiosis: a critical step of cell division required in the development of mature eggs and sperm, a scientist explained to The Guardian.

 
An engineering challenge

“The next steps are an engineering challenge,” as described by Amander Clark, who works on lab-grown gametes at the University of California. Clark told The Guardian it could probably be achieved in 10 to 20 years.

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