Pig Kidney Functions for 271 Days in U.S. Man, Setting New Record

A pig kidney transplanted into a human body has remained functional for 271 days, setting a new record. U.S. doctors said this is the longest period to date that a genetically modified pig kidney has remained functional after being transplanted into a human.

The patient, Tim Andrews, had severely damaged kidneys due to Type 2 diabetes. A genetically modified pig kidney was transplanted into his body on January 25, 2025, when he was 66. The kidney began functioning immediately after the transplant and filtered his blood for 271 days.

Andrews said the treatment gave him new hope for life. While the kidney was functioning, he did not have to go to the hospital for dialysis for several months. He said the prospect of being free from the dialysis machine and living a normal life was his greatest hope.

The medical team at Mass General Brigham said the success demonstrated the potential of using pig organs as a “bridge” until a human kidney becomes available. The approach could become an important future option, particularly for patients who have to wait a long time for a kidney from a human donor.

However, the pig kidney stopped functioning after 271 days, and doctors removed it. Andrews then underwent dialysis for 82 days. Later, in January 2026, he received a human-donor kidney. Doctors said the new kidney is functioning well.

Andrews had been told that he might have to wait up to seven years for a kidney from a human donor. The prospect of remaining on dialysis for a long time was also a concern for him. He said the situation was becoming increasingly discouraging as time ran short. Therefore, he viewed the opportunity to receive a pig kidney transplant as “hope” and “the light at the end of the tunnel.”

The shortage of kidneys needed for transplantation has long been a problem. In the United States, around 100,000 people are waiting for a kidney transplant, while only about 25,000 kidney transplants can be performed there each year. In the United Kingdom, more than 7,000 people are also on the waiting list for a kidney transplant.

Because of the shortage of organs, scientists have long been researching ways to transplant organs from other animals into humans. This approach is known as xenotransplantation. Researchers consider pigs suitable animals for this type of treatment because their organs are similar in size to human organs and there is extensive experience in raising pigs.

However, when a kidney from an ordinary pig is transplanted into a human, the immune system may identify it as a foreign organ and attack it. Therefore, researchers have developed genetically modified pigs. The kidney transplanted into Andrews was taken from a Yucatan miniature pig whose genes had been modified at 69 sites.

These genetic modifications removed certain characteristics from the pig’s cells that could be easily identified and attacked by the human immune system. Some human genes were also added to help shield the pig tissue from the immune system. Measures were also taken to deactivate potential viruses present in the pig’s DNA.

After the transplant, early signs of an immune response against Andrews’ kidney were observed. The condition was brought under control by adjusting his medication. However, after about six months, damage and inflammation developed in the kidney’s blood vessels, and it eventually stopped functioning. Doctors could not determine with certainty exactly why the kidney failed.

Dr. Leonardo Riella of Mass General Brigham said the shortage of donor organs is a major problem. Xenotransplantation could become an option in the future for patients who do not have a living human donor and depend on dialysis for long periods.

Doctors said Andrews’ case has demonstrated the potential of transplanting pig organs into humans, while also highlighting the major challenges that remain in ensuring long-term safety and effectiveness. More research is needed.

Source: BBC