Japan approves the creation of hybrid embryos between rodents and humans

Japan is funding a scientific team that plans to grow animal embryos in which human cells have been inserted, for the first time since the legalization of the procedure in March. The decision was made on July 24 by a committee of the Ministry of Education, Culture, Sports, Science and Technology, reports The Asahi Shimbun.

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

The planned development in these embryos of a pancreas integrating human cells could contribute to the emergence of a new method of creation of transplantable organs, says project leader, Hiromitsu Nakauchi, of Tokyo and Stanford Universities.

"We do not plan to immediately create human organs, but it allows us to advance our research, based on the knowledge gained so far," he told the newspaper.

Scientists are considering similar experiments – and probably in other animals, such as pigs and sheep – to create livers and kidneys, if the project succeeds.

Ethical issues

Despite Nakauchi's claim that genetic modification will make embryos "send cells [iPS] only the pancreas, "part of the scientific community worries about the possible proliferation of human cells in other tissues, including those of the brain, rodents.

"There is a risk that a certain part of the body becomes an unexpected chimera, a condition in which heterologous cells exist in a body [procedentes de otra especie], mixing human cells in the brain or reproductive cells of rats and mice, "said biologist Jiro Nudeshima at The Asahi Shimbun.

For its part, the team intends to observe the animals for two years and ensures that it will close the experiment if the proportion of human cells in its neurons exceeds 30%.

RT