TOKYO -- A Japanese research team announced on Nov. 25 that it has successfully transplanted a pig kidney genetically modified for humans into a monkey, marking Japan's first case of cross-species transplantation with such an organ.

The team including Kawasaki-based venture company PorMedTec Co. Ltd. a spinoff of Tokyo's Meiji University, hopes to move ahead with clinical research involving humans as early as 2026.

Xenotransplantation, which involves transplants between different species, has already been performed in the United States and China, with genetically modified pig hearts and organs being transplanted into humans, and the organs have been confirmed to function. In February this year, PorMedTec also produced genetically modified pigs for the first time with a view to transplanting their organs into humans.

The research team says 36 genetically modified piglets have been born to date, and 13 of them are currently being raised. In the latest transplant, a kidney from one 9-kilogram pig aged 2 1/2 months was transplanted into a male crab-eating macaque that had had both of its kidneys removed. It was confirmed that blood flowed normally into the kidney transplanted into the monkey and normal urination was observed. Researchers will observe the treated macaque for about half a year. By sometime in 2025, the team hopes to conduct transplants into monkeys at a rate of about one a month to gather data.

Xenotransplantation is seen as a potential solution to the shortage of human organs for transplants. Hiroshi Nagashima, CEO and chief scientist of PorMedTec, who is also a professor of reproductive biology at Meiji University, commented, "It takes seven months to raise a pig for a human-bound transplant, and so we want to consider efficient ways of breeding them. In the United States, there is a lot of experimental data between pigs and monkeys, and so we want to compare that with the data in Japan and progress to research involving humans as soon as possible."

Team member Hisashi Sahara, a professor of transplant surgery at Kagoshima University, commented, "We would like to steadily advance research on transplantation into monkeys, and open the path to practical applications."

(Japanese original by Ryo Watanabe, Lifestyle, Science & Environment News Department)