Monkeys receive pig organ transplants

A team of scientists in China has successfully transplanted multiple organs from a pig into four monkeys, three of which survived the surgery, marking what experts say is a big step forward in xenotransplantation research aimed at tackling the shortage of donated organs for humans.

After 14 hours of surgery on Oct 16, the liver, kidneys, heart, corneas, skin and bones of a genetically modified pig were transplanted into four monkeys at the Xijing Hospital of the Air Force Medical University in Xi'an, Shaanxi province.

The transplanted organs and tissues functioned well and three of the monkeys were in stable condition as of Monday. The monkey that received the liver and kidney transplants died on Sunday. It was the first time that multiple organs and tissues had been transplanted from one donor to several recipients of a different species at the same time, according to a news release from the hospital on Thursday.

With advances in surgical techniques, human organ transplantation has become part of conventional treatment for many diseases, with the long-term survival rate and living quality of patients improving, experts said.

But the shortage of donors has greatly limited the development of the life-saving medical procedure. As pigs' organs are similar to those of humans in size and shape, genetically modified pigs are considered globally as the most ideal donor for xenotransplantation, or cross-species organ transplantation, according to experts.

The success of the latest surgery expands the clinical application of xenotransplantation and offers scientific data and technology to tackle the shortage of donated organs, said Dou Kefeng, a professor at the hospital and the lead doctor for the surgery.

Dou said the genetically modified pig had three genes removed to avoid triggering transplant rejection in the recipients. Three human genes were also added to the genome of the pig to address any blood-related disorders and decrease damage to the transplanted organs.

There are still many challenges in applying the experience to human organ transplantation, Dou said. Gene modification needs to be precisely designed to meet the demands of different organs, he said. More immunosuppressants also need to be used for the recipient, which will increase side effects. Some key immunosuppressants used in animal experiments have not been approved for human clinical application.

There are also concerns about whether bacteria, viruses, fungi and parasites from the pig would enter the human body and trigger infection, although there is evidence that such problems can be avoided, Dou said.

If the patients have better treatment options, they are also not suitable for such clinical experiments, he said, adding that more non-human primate experiments should be conducted to obtain sufficient and stable data to give the most ideal gene modification and immunosuppression protocols.

"Xenotransplantation not only enlarges the source of donated organs and tissues, it is also a major breakthrough in medical development. It will drive the advance of many new biological and clinical technologies, and finally benefit humans," he said.

In September 2021, researchers at New York University transplanted a kidney from a genetically engineered pig to a clinically brain-dead human with the consent of her family. Researchers said the kidney worked for 54 hours and there were no signs of the body rejecting it. More pighuman kidney transplant trials were conducted that year in the United States.

In January 2022, a 57-year-old man received a genetically modified pig heart in a first-of-its-kind transplant surgery at the University of Maryland Medical Center and died two months after the operation.