A genetically edited pig kidney functioned inside a 66-year-old American man for 271 days, the longest such period on record, according to doctors at Mass General Brigham in the United States. Tim Andrews, who had end-stage kidney disease, received the animal organ in January 2025 as a temporary “bridge” while he awaited a transplant from a human donor. He lived successfully with the pig kidney for 271 days before moving to short-term dialysis and then receiving a donor human kidney, the team reported in the Lancet medical journal.
First Transition from Pig to Human Kidney Transplant
Doctors said this case marks the longest dialysis-free survival after a pig-kidney transplant in a living human and the first transition from pig-to-human kidney transplantation. The procedure was performed by the team from Mass General Brigham, with lead author Dr Leonardo Riella from the Centre for Transplantation Sciences.
Dr Riella highlighted the organ shortage crisis, stating: “The organ shortage is the greatest crisis we have right now in transplantation. 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.” He added 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 long-term safety and durability are established, as a destination therapy in its own right.
Previous Pig-Kidney Transplant Case and Global Context
Another pig-kidney transplant to a living human was undertaken in 2024 at Massachusetts General Hospital, where the patient survived 52 days before dying from heart issues unrelated to the transplant. Dr Rommel Ravanan, a consultant nephrologist and chief medical officer for the UK’s NHS Blood and Transplant, noted that the US and China have reported several similar transplants since 2022.
Dr Ravanan explained: “Advances in genetics technology enable teams to ‘knock out’ some of the pig genes, so the human body is less able to recognise the organ was different.” This genetic modification is central to reducing the risk of rejection, allowing the pig organ to function for extended periods. The successful 271-day period in Mr Andrews’ case demonstrates the potential of xenotransplantation as a viable option for patients with end-stage kidney disease who face long waits for human organs.
Implications for Organ Shortage and Future Treatment
The findings published in the Lancet underscore the growing role of xenotransplantation in addressing the global shortage of donor organs. With thousands of patients on waiting lists, the ability to use pig kidneys as a bridge could reduce reliance on dialysis and improve outcomes for those awaiting human transplants. The case also provides critical data on the safety and durability of pig organs in living humans, informing future clinical trials and potential wider adoption of this approach.
As research progresses, doctors like Dr Riella envision a future where xenotransplantation might serve not only as a temporary measure but as a long-term solution, known as destination therapy. For now, the record-setting 271-day survival marks a significant step forward in the field, offering hope to patients with renal failure who currently depend on dialysis while waiting for human donor kidneys.
