Japan Gives Green Light to the Creation of Hybrid Human-Rodent Embryos

"There is also a risk that a certain body part unexpectedly becomes a chimera, a condition in which heterologous cells exist in one body, by mixing human cells into the brains or reproductive cells of rats and mice.”

The green light was given this July 24 by a committee of the Ministry of Education, Culture, Sports, Science, and Technology of the Asian country. The decision reverses a previous one made earlier this year, which banned the procedure in Japan.

According to the project, biologists will reformulate the genes of fertilized ovules of rats and mice, blocking the mechanism of pancreas creation. Then, they will be equipped with induced pluripotent stem cells (iPS), taken from humans, which can be transformed into any tissue, and inserted into the wombs of the rodents.

“Finally, we are in a position to start serious studies in this field after 10 years of preparation,” scientist Hiromitsu Nakauchi was quoted as saying in the Asahi Shimbun, a Japanese newspaper.

“We don’t expect to create human organs immediately, but this allows us to advance our research-based upon the know-how we have gained up to this point.”

The development in these embryos of a pancreas that combines human cells could contribute to the emergence of a new method of creating transplantable organs, explains the project leader Nakauchi, from the universities of Tokyo and Stanford.

The researchers revealed that they do not expect to create transplantable human organisms in the near future, but the project will help experts advanced their researcher, based on the knowledge they’ve acquired so far.

Scientists are already considering similar experiments – and probably in other animals, such as pigs and sheep that will give rise to the creation of livers and kidneys, if pf course the project is successful.

But despite Nakauchi’s claim that the genetic modification will make embryos “send cells [iPS] only to the pancreas,” a part of the scientific community is concerned about the possible proliferation of human cells in other tissues – among them, those of the brain— of rodents.

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If the project succeeds, the researchers could create a transplantable pancreas.

Unsurprisingly perhaps, scientists have already managed to successfully create a pig/human chimeric embryo in 2017 and a sheep/human hybrid in 2018.

Jiro Nudeshima, a specialist who co-heads a civic group concentrating on the ethical concerns raised by life science research, revealed serious doubts about the efficacy of the study, reports Asahi.

“If the goal of such studies is to discover a therapeutic application for humans, experiments on rats and mice are unlikely to produce a useful result because the size of the organ will not be sufficient and the result will be a far cry from humans anatomically,” Nudeshima said.

“It is problematic, both ethically and from a safety aspect, to place human iPS cells, which are still capable of transforming into all types of cells, into the fertilized eggs of rats and mice,” he added. “There is also a risk that a certain body part unexpectedly becomes a chimera, a condition in which heterologous cells exist in one body, by mixing human cells into the brains or reproductive cells of rats and mice.”

Via
The Asahi Shimbun