Pig kidney functions for record 271 days inside man awaiting human transplant
Surgeons Leonardo Riella and Tatsuo Kawai with patient Tim Andrews after Andrews’ xenotransplant in 2025. (Kate Flock/Massachusetts General Hospital)
A man who lived with a pig kidney for 271 days before later receiving a human organ shows how the practice of xenotransplantation could help bridge the gap for patients on the donor list, a new paper found.
The Mass General Brigham paper was published Sept. 3 in The Lancet.
Tim Andrews’ pig kidney transplant
The backstory:
According to a news release from Mass General Brigham, 66-year-old Tim Andrews received a genetically modified pig kidney transplant in January 2025. The pig organ transplant – known as xenotransplantation – allowed Andrews to skip dialysis for 271 days before he had the organ removed Oct. 23 because its function was declining.
Andrews resumed dialysis before receiving a human kidney transplant in January 2026.
What they're saying:
Researchers say Andrews’ case is a prime example of how xenotransplantation could "bridge the gap between end-stage kidney failure and a human transplant, allowing a patient to forgo dialysis in the meantime."
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"The organ shortage is the greatest crisis we have right now in transplantation," said lead author Dr. Leonardo Riella, of the Center for Transplantation Sciences and the Division of Nephrology at Mass General Brigham. "We know that the best treatment option for patients with end-stage kidney disease who have developed renal failure is transplantation, but we simply don’t have enough human organs to transplant in a timely manner. Our vision is that xenotransplantation could help address this gap—initially as a bridge to get patients off dialysis while they wait for a human donor kidney, and potentially, as we establish long-term safety and durability, as a destination therapy in its own right."
The history of xenotransplantation
Dig deeper:
Andrews’ experience illustrates lessons researchers have learned with each experiment. The first attempts using pig organs gene-edited to be more humanlike – two hearts and two kidneys – were short-lived.
FILE VIDEO: First pig kidney transplant in human
Boston doctors performed the first transplant of a genetically modified kidney from a pig to a living human (2024)
The first one in 2024, also at Massachusetts General Hospital, resulted in the patient surviving 52 days before death from cardiac causes unrelated to the transplant.
RELATED: Alabama woman has pig kidney removed after a record 130 days
Then researchers began considering patients not nearly as sick as prior recipients for these experiments — and an Alabama woman’s pig kidney lasted 130 days before it had to be removed last spring, the record Andrews surpassed.
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By the numbers:
More than 100,000 people, most needing kidneys, are on the U.S. transplant list, and thousands die waiting.
"The patients are the true pioneers here," Riella said. "By stepping forward and being willing to participate in these early-stage studies, they are advancing the science. Without their trust and courage, we would not be able to do what we do."
The Source: This report includes information from Mass General Brigham hospital and The Associated Press.