Gene-Edited Pig Kidney Functions for 271 Days in Patient, Offering Hope for Future Transplants

September 4, 2026: A genetically modified pig kidney functioned in a US patient for 271 days, marking the longest reported period of dialysis-free survival following a pig-to-human kidney transplant in a living person. The case has been described as an important development in the emerging field of xenotransplantation.

Tim Andrews, who was 66 when he received the transplant, said the procedure gave him hope and allowed him to spend months without undergoing regular dialysis while he waited for a human donor kidney.

The transplant was carried out at Mass General Brigham in Massachusetts on January 25, 2025. Andrews had end-stage kidney disease associated with type 2 diabetes and did not have a suitable living donor.

The genetically edited kidney began functioning immediately after transplantation, according to the medical team. The organ was designed with multiple genetic modifications intended to reduce the risk of immune rejection and limit the possibility of pig-derived infections.

How xenotransplantation could help

Xenotransplantation refers to the transplantation of organs or tissues between different species. Researchers are studying the approach as a possible way to address the shortage of human donor organs.

Pigs are considered promising donors because their organs are broadly comparable in size to human organs. However, the human immune system can recognise pig tissue as foreign and attack the transplanted organ.

To address this challenge, researchers have genetically modified donor pigs. The kidney used in Andrews's transplant underwent extensive genetic engineering designed to reduce immune rejection, introduce human-compatible biological features and address the risk of pig-derived viruses.

Kidney function continued for 271 days

Doctors reported that Andrews experienced an early episode of immune rejection, which was treated successfully. He was subsequently able to remain free from dialysis for 271 days.

After several months, the transplanted kidney developed blood-vessel damage and inflammation, and its function gradually declined. The exact cause of the late-stage failure remains an important area of investigation.

The pig kidney was eventually removed, after which Andrews temporarily returned to dialysis. In January 2026, he received a kidney from a human donor, which has reportedly continued to function well.

A potential bridge to human transplantation

Researchers at Mass General Brigham say the case demonstrates the potential of a genetically modified pig kidney to act as a temporary “bridge” for patients waiting for a human donor organ. Such an approach could potentially reduce the time patients spend on dialysis while they await transplantation.

Dr Leonardo Riella, from Mass General Brigham's Center for Transplantation Sciences, said the shortage of donor organs remains a major challenge and that xenotransplantation could eventually help address this gap.

However, researchers stress that xenotransplantation remains an emerging medical field. Further research and clinical studies will be required to determine the long-term safety, effectiveness and durability of genetically modified pig organs in humans.

A significant milestone, but more research is needed

Andrews's experience represents the first reported case in which a patient received a genetically modified pig kidney and later successfully transitioned to a human kidney transplant. The 271-day period also sets a new reported milestone for dialysis-free survival following porcine kidney xenotransplantation in a living human.

The case highlights both the progress and the remaining challenges in developing animal organs as a potential source of transplants for people facing long waits for human donor organs.

Source: Mass General Brigham, The Lancet and current media reports