A genetically modified pig kidney kept a 66-year-old man with kidney failure free of dialysis for a record nine months in a first-of-its-kind bridge transplant. That gives hope in a world where the number of people waiting for organ transplants exceeds the number of organs available. According to a new report published in The Lancet, pig kidney transplants could offer a solution for patients facing long waiting times for human kidneys. The study patient, a 66-year-old living with kidney failure caused by type 2 diabetes who had been on haemodialysis — a medical treatment that uses a special machine to filter waste products, extra fluids, and toxins from the blood when the kidneys fail — for two years before transplantation, received the pig organ in January 2025. The patient had no available living donor and was listed for deceased-donor kidney transplantation, for which the expected waiting time was over five years.Based on the Kidney Transplant Decision Tool — a programme that weighs treatment options and waiting times — the estimated probability of receiving the transplant he needed was approximately 9%, whereas the estimated risk of death or removal from the waiting list exceeded 40%. The pig kidney featured 69 genomic modifications to improve compatibility and safety, and successfully provided dialysis-free support for 271 days. From pig kidney to human donor According to the researchers, the transplanted organ started working immediately. Nine months after the transplant, the kidney was removed. The patient did not show any signs of antibodies against human tissue, which would have made it nearly impossible for him to accept a human kidney, or any animal-borne infections. After the pig kidney started to fail, it was extracted, and the patient successfully received a human kidney transplant from a deceased donor and maintained stable organ function.He received the human kidney earlier than expected because doctors found a donor organ with the highest possible level of tissue compatibility.This level of compatibility is, according to the researchers, “uncommon and largely unpredictable”, and under standard organ allocation policies, it confers substantial priority. Addressing organ shortagesTransplanting genetically engineered pig organs has been proposed as a solution to the organ shortage. However, the first pig kidney transplant into a living person, in 2024, ended after 52 days when the patient died from unrelated heart problems, and no previous studies had documented xenograft — transplant between species — survival beyond two months.“This case illustrates both the promise and the remaining challenges of clinical kidney xenotransplantation,” the authors wrote. According to the researchers, these findings suggest that animal organs could serve as a bridge to traditional transplants for patients facing long wait times for human organs. “The organ shortage is the greatest crisis we have right now in transplantation,” said lead author Leonardo Riella at Mass General Brigham.”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.”Yet, they warn that this is a single patient with no comparison group, and that the outcome reflects careful patient selection and intensive specialist care that may not be available elsewhere.