A pig kidney transplanted into a human lasted 271 days in the patient's body, the longest life of an organ transplanted from an animal to a human, doctors at Boston's Mass General Brigham hospital and research center system reported in a publication in the Lancet journal.
Transplant patient Tim Andrews, 66, said the operation gave him "hope" and saved him from spending months in hospital undergoing dialysis.
A team of doctors at Mass General Brigham Hospital say their work shows that pig organs could be used as a "bridge" option for patients waiting for a human organ to become available for transplantation.
Nine months after transplantation, the pig kidney stopped functioning in the patient's body and was removed. Tim Andrews required a short course of dialysis after having a kidney removed. He later received a kidney transplant from a donor.
Due to the shortage of organs for transplantation, scientists are exploring the possibility of xenotransplantation—the use of animal organs for transplantation into humans. In the United States, about 100,000 people are waiting for a kidney transplant, while only 25,000 kidney transplants are performed annually. In the UK, more than 7,000 people are on the waiting list for a kidney transplant.
Doctors have warned Tim Andrews, who suffers from kidney failure, that the wait for a donor kidney could take seven years, while patients on chronic dialysis live on average about five years.
“I was a little short on time [to live to see the donor kidney]... it was very depressing,” admits Tim Andrews. According to him, the idea of a kidney transplant from a pig became “hope” and “light at the end of the tunnel” for him. “Hope is the most important thing, a chance to be free of the [dialysis] machine and live your life,” says Tim Andrews.
Pigs are considered the most suitable animals for organ transplantation to humans, since their organs are very similar in structure and size to human ones. But you can't just take a kidney from a pig and transplant it into a human. The human body will immediately recognize the organ as foreign and the process of rejection will begin. Therefore, researchers take organs from genetically modified Yucatan pigs for transplantation. In order to make their organs as similar to human ones as possible, 69 modifications were made to the pig genome. These modifications eliminate certain features of pig cells that the human immune system recognizes as foreign and attacks. A number of modifications are aimed at eliminating human infections with swine viruses.
Tim Andrews had end-stage renal failure due to type 2 diabetes. His kidneys essentially stopped working. He was 66 years old when he underwent xenotransplantation on January 25, 2025. According to details published in the medical journal Lancet, the transplanted pig kidney started working immediately in the patient's body. The kidney continued to function for 271 days until it was removed in October of that year. Andrews then required hemodialysis for 82 days until he received an organ from a donor in January this year. The donor organ transplanted to him is working well.
Dr. Leonardo Riella of the Transplant Center at Mass General Brigham said the shortage of organs available for transplant means "we are in a crisis." “We work very hard to give hope to patients, and we really believe that xenotransplantation can be an alternative for patients who do not have a donor. This way we can do without dialysis and bring them to a donor organ transplant,” he said.
Tim Andrews initially showed signs of organ rejection by the immune system after a pig kidney transplant, but doctors were able to stop this process by adjusting the treatment. However, after about six months, the blood vessels in the kidney began to become damaged, and the organ became inflamed and began to fail.
