A Japanese research team said Thursday it has begun drafting guidelines to facilitate the safe xenotransplantation of genetically modified animal organs to humans, as experiments involving pig-to-human transplants of kidneys and hearts gain traction abroad.

The team from the state-backed Japan Agency for Medical Research and Development aims to finalize the guidelines by fiscal 2025 in hopes the groundbreaking procedures could help address the global shortage of human organ donors.

But with xenotransplantation involving the transplantation of live cells, tissues or organs from one species to another, concerns remain regarding the transmission of unrecognized diseases to recipients and, in turn, the general human population.

File photo taken in November 2013 shows an operating room at Hiroshima University Hospital in Hiroshima, western Japan. (Kyodo)

In Japan, there is ongoing research on transplanting pig islet cells into type 1 diabetes sufferers, with the health ministry in 2016 revising guidelines on risks associated with the procedure. The guidelines, however, do not cover the transplantation of entire organs from animals.

The AMED research team now aims to standardize the entire procedure for domestic implementation, from the breeding of pathogen-free pigs to the harvesting of organs for transplantation.

The team will specifically examine areas such as quality control to ensure pigs are raised in sterile environments, to set the optimal number of days pigs can be raised within organ procurement facilities, and determine the necessary tests to be conducted before and after transplantation.

Researchers will also evaluate a process of selecting potential recipients and immune suppression therapies suited to xenotransplantation.

"We want to ensure that the concept of xenotransplantation becomes correctly recognized by society as a viable new option," said Hisashi Sahara, an associate professor of transplant immunology at Kagoshima University who leads the team.

The team also includes researchers specializing in porcine-derived medical products and transplantation-related immune responses, as well as clinical physicians and regulatory experts.

In January 2022, a groundbreaking surgery in the United States marked the world's first xenotransplantation of a pig heart -- with 10 genetic modifications to prevent immune rejection and abnormal inflammatory response -- into a man dying of heart failure. The man survived approximately two months after the procedure.

Researchers in the United States have also previously conducted xenotransplantation of genetically modified pig kidneys to brain-dead human patients.