A 66-year-old man with end-stage kidney failure has become the first person to successfully use a genetically modified pig kidney as a bridge to a human transplant, living for nine months without dialysis. The case, reported in The Lancet, offers a potential answer to the chronic shortage of donor organs that leaves thousands of Europeans waiting years for a transplant.
The patient, whose kidney failure stemmed from type 2 diabetes, had been on haemodialysis for two years before receiving the pig organ in January 2025. With no living donor available and a projected wait of more than five years for a deceased-donor kidney, his chances of receiving a transplant were estimated at just 9%, while the risk of death or removal from the waiting list exceeded 40%.
The pig kidney carried 69 genomic modifications designed to improve compatibility and reduce the risk of rejection. It began producing urine immediately and sustained the patient without dialysis for 271 days. When the organ eventually showed signs of failure, it was removed, and the patient received a human kidney from a deceased donor—sooner than expected because doctors found a tissue match of the highest possible compatibility.
A milestone for xenotransplantation
Previous attempts at pig-to-human kidney transplants have been short-lived. The first such transplant into a living person, in 2024, ended after 52 days when the patient died from unrelated heart problems. No earlier case had documented survival beyond two months. This new report, published in The Lancet, is the first to show that a pig kidney can function for an extended period and then be safely replaced by a human organ.
“This case illustrates both the promise and the remaining challenges of clinical kidney xenotransplantation,” the authors wrote. They noted that the patient developed no antibodies against human tissue—a key barrier to future transplants—and no animal-borne infections were detected.
Lead author Leonardo Riella, a transplant nephrologist at Mass General Brigham in Boston, framed the achievement in stark terms: “The organ shortage is the greatest crisis we have right now in transplantation.” He added, “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 findings come as European health systems grapple with similar pressures. In Germany, for example, more than 8,000 people are on kidney transplant waiting lists, yet only about 2,000 transplants are performed each year. Across the European Union, the gap between supply and demand has prompted several member states to explore cross-border organ sharing and to fund research into alternative sources.
While the pig kidney used in this case was not a European product, the research has direct implications for European transplant centres. The authors stress that the approach is still experimental and that long-term safety data are lacking. Ethical and regulatory frameworks for xenotransplantation vary widely across the continent, and the European Medicines Agency has yet to issue formal guidance on such therapies.
For now, the case stands as a proof of concept. It demonstrates that a genetically engineered animal organ can keep a patient alive and well enough to receive a human transplant later. As Riella put it, the goal is not to replace human donation but to buy time for those who have none.
