An American patient lived for 271 days with a genetically modified pig kidney before receiving a human kidney

Tim Andrews, 66 years old, from the state of New Hampshire in the New England region of the northeastern United States, was suffering from end-stage renal failure as a result of type 2 diabetes, before he underwent this pioneering procedure in the United States in January 2025.

Doctors explained that the animal organ, which was taken from a Yucatán miniature pig and genetically modified to be compatible with the human immune system, served as a temporary "bridge" while Andrews waited for a transplant from a human donor. He successfully lived with the genetically modified organ for 271 days, before transitioning to a short period of dialysis, then receiving a kidney from a human donor.

The medical teams said that this station represents the longest period of survival without dialysis recorded after transplanting a pig kidney into a living patient, and the first successful transfer from transplanting a pig kidney to a human kidney. The kidney was transplanted in January 2025 and began working immediately, but about six months later, vascular damage to the kidney developed that progressed to organ failure, and the pig kidney was removed. Andrews later received a kidney from a deceased human donor.

In a CNN documentary, Andrews described the pig kidney transplant as a "miracle," adding that he was now able to cook, clean the house, and take long walks with his dog.

No porcine viruses or other pathogens were detected at any time, the researchers said, adding that the findings support porcine kidney transplantation as a potential bridge for people waiting long periods for a human kidney, while emphasizing the need for more research.

The team, from academic centers and hospitals at Massachusetts General Hospital, recently published their findings in The Lancet medical journal.

Lead author Dr. Leonardo Rella, from the Center for Transplantation Sciences at Massachusetts General Hospital, said: “Organ shortage is the biggest crisis we now face in the field of transplantation. We know that the best treatment option for patients with end-stage renal failure is transplantation, but we simply do not have enough human organs to transplant in time. We believe that transplanting organs from animals can help fill this gap, either as a temporary bridge or as a permanent treatment in the future.” He praised the courage of the patients who make this progress possible.

Another pig kidney transplant to a living patient was performed in 2024 at Massachusetts General Hospital, where the patient survived 52 days before dying due to heart problems unrelated to the transplant.