a pig kidney transplantIntroduced into an American patient it worked for 271 days, setting a record for the longest period that a genetically modified pig organ has functioned inside a human being.
The transplant gave Tim Andrews, who had end-stage kidney disease caused by type 2 diabetes, more than nine months without dialysis while he waited for a kidney from a human donor.
Doctors at Mass General Brigham in the United States said the case provides further evidence that pig organs could one day serve as a temporary “bridge” for patients waiting for a human transplant.
Andrews was 66 years old when he received the pig kidney on January 25, 2025. The organ began working immediately and continued to function until doctors removed it in October of that year.
He then underwent dialysis for 82 days before receiving a kidney from a human donor in January 2026, which continued to function well.
For Andrews, the transplant was a relief from the uncertainty surrounding his condition. He had been told he could wait up to seven years to get a human kidney, while the average life expectancy of people on dialysis is about five years.
“I was a little short on time… it gets very depressing,” he said.
He called the possibility of receiving a pig kidney “hope” and the “light at the end of the tunnel.”
“Hope is the most important thing, the opportunity to be free from [dialysis] machine and live your life.”
The procedure is part of growing research into xenotransplantation, which involves transplanting organs from animals to humans as a way to address the shortage of donor organs.
Pigs are considered suitable for research because their organs are very similar in size to human organs and the animals can be raised under controlled conditions.
However, a normal pig kidney would trigger an immediate and severe immune response in a human recipient. To do this, the researchers used miniature pigs from Yucatan, whose organs had undergone 69 genomic modifications.
The modifications were designed to remove features of pig cells that the human immune system recognizes and attacks, introduce human DNA to make the tissue less visible to the immune system, and deactivate viruses embedded in the pig’s genetic material to reduce the risk of infection.
In Andrews’ case, doctors initially detected signs that her immune system was rejecting the transplanted kidney. They managed the reaction by adjusting their medication.
The organ subsequently developed blood vessel damage after about six months, leading to inflammation and a gradual loss of function. Doctors said they could not establish the precise cause because there was no evidence that the antibodies attacked the pig’s kidney.
The need for alternative sources of kidneys remains significant. In the United States, about 100,000 people are waiting for a kidney transplant, while approximately 25,000 kidney transplants are performed each year. More than 7,000 people in the UK are also on the kidney transplant waiting list.
Dr. Leonardo Riella of Mass General Brigham’s Transplant Science Center said the gap between demand and availability of organs had created an urgent situation.
The research team believes that xenotransplants could eventually help patients who do not have a living donor and potentially allow them to avoid prolonged dialysis while they wait for a human kidney.
Dr Riella said the shortage of organs available for transplants meant “we are in a crisis”.
“We are working very hard to bring hope and we really feel that xenotransplantation can be an alternative for patients who do not have a living donor, where we could potentially avoid dialysis and get them to a transplant,” he said.
Doctors acknowledged that the 271-day result also highlights the challenges that remain before pig kidneys can become a routine treatment.
In their article in The Lancet, the doctors state: “This case illustrates both the promise and remaining challenges of clinical kidney xenotransplantation.”
(BBC News)
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