Transplanted pig kidney works in US man's body for record 271 days

A pig kidney that was transplanted into an American man lasted 271 days inside his body, marking the longest recorded time for such a procedure, according to US doctors. Tim Andrews, the recipient, expressed hope that the transplant would spare him from relying on a dialysis machine for months. The team at Mass General Brigham hospital, which performed the surgery, stated that their work demonstrates the potential for pig organs to serve as a bridge until a human transplant is available.

However, the pig organ eventually failed and was removed, requiring Andrews to undergo a short period of dialysis before receiving a donor kidney.

Doctors and scientists are actively exploring xenotransplantation, or the use of organs from other species, due to the significant shortage of organs available for transplants. In the United States, around 100,000 individuals are waiting for a kidney, while only 25,000 transplants occur each year. In the UK, more than 7,000 people are on the kidney transplant list.

Andrews was initially informed that it could take up to seven years to reach the top of the transplant list, but living on dialysis typically reduces one's lifespan to about five years.

Andrews expressed that the prospect of a pig transplant provided him with hope and a sense of relief from the burdens of dialysis. He described the idea of a pig transplant as a "light at the end of the tunnel." The success of the pig kidney transplant hinges on careful modifications to Yucatan miniature pigs, which have undergone 69 genomic changes to humanize their organs.

These modifications involve removing pig cell features that trigger the human immune system's rejection response, adding human DNA to mask the pig tissue, and disabling viruses that reside within pig DNA to prevent infection.

Andrews, who had end-stage kidney disease due to type 2 diabetes, underwent the xenotransplant surgery on January 25, 2025. The transplanted pig kidney functioned immediately, as reported in a study published in the Lancet medical journal. However, after 271 days, the kidney was removed, and Andrews subsequently needed dialysis for 82 days.

He later received a donor kidney that has been functioning well. Dr. Leonardo Riella from the center for transplantation sciences at Mass General Brigham noted that the shortage of transplantable organs has created a crisis in the medical field, and xenotransplantation could offer a promising alternative for patients without living donors.

The doctors emphasized that while they witnessed early signs of the patient's immune system rejecting the pig kidney, the reason for the kidney's eventual failure remained unclear.