In a world first, Japanese team creates eggs and sperm of endangered species from iPS cells


A Japanese research team has created eggs and sperm of Ryukyu spiny rats by using induced pluripotent stem cells — the first time reproductive cells of an endangered species have been produced from iPS cells.

The research by scientists from the University of Miyazaki, Hokkaido University, Kyoto University, Shiga University of Medical Science and the research institute Riken were published on Friday in the U.S. journal Science Advances.

The method will be effective in combatting extinctions, said Arata Honda, a researcher at the University of Miyazaki who took part in the study.

Ryukyu spiny rats, Tokudaia osimensis, are registered as a natural treasure. They are only found on the island of Amami Oshima in Kagoshima Prefecture. The species is threatened by habitat destruction, predation by cats, dogs and mongooses, and competition with introduced black rats.

The team created iPS cells from rats and injected them into mouse embryos, which were transplanted into the uteri of mice.

The resulting baby mice contained cells of the endangered rats, including small amounts of Ryukyu spiny rat sperm and eggs in their testicles and ovaries.

Through further studies, the research team will attempt to produce Ryukyu spiny rats using the new reproductive cells.

“Our current technology is still far from reaching such a target, but there is a possibility,” Honda said.

Research overseas has succeeded in creating iPS cells of several endangered animals, including monkeys, but none managed to produce eggs and sperm, according to the Japanese team.

Being able to use mice, which share similar characteristics with the endangered rats, has aided the research, the team said.