A genetically modified pig kidney has functioned successfully in a living human for 271 days, setting a new record for the longest dialysis-free survival following a pig-to-human kidney transplant.
The procedure was carried out on Tim Andrews, a 66-year-old American with end-stage kidney disease, in January 2025.
Doctors at Mass General Brigham said the transplanted pig kidney was used as a temporary “bridge” to keep Andrews off dialysis while he waited for a suitable human donor kidney.
According to the team, Andrews lived successfully with the genetically edited pig kidney for 271 days before undergoing a short period of dialysis and later receiving a human donor kidney.
The doctors described the case as the longest recorded period a living human has remained dialysis-free after receiving a pig kidney. They also said it marked the first reported transition from a pig kidney to a human donor kidney.
The findings were published in the medical journal *The Lancet* by researchers from Mass General Brigham in the United States.
Dr Leonardo Riella, lead author and a specialist at the Centre for Transplantation Sciences at Mass General Brigham, said the shortage of human organs remains a major challenge in transplantation.
“The organ shortage is the greatest crisis we have right now in transplantation,” Riella said.
He explained that while transplantation remains the preferred treatment for patients with end-stage kidney disease, the limited supply of human organs means many patients have to remain on dialysis while waiting for a donor.
Riella said xenotransplantation — the transplantation of organs between different species — could initially provide a temporary solution for patients awaiting human organs.
“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,” he said.
The latest case follows an earlier pig-kidney transplant performed on a living patient at Massachusetts General Hospital in 2024. That patient survived for 52 days before dying from heart complications that doctors said were unrelated to the transplanted kidney.
Dr Rommel Ravanan, a consultant nephrologist and chief medical officer for UK-based NHS Blood and Transplant, said several similar pig-to-human transplants have been reported in the United States and China since 2022.
He said advances in genetic engineering have enabled scientists to modify pig organs to reduce the likelihood of rejection by the human immune system.
Researchers hope further advances in xenotransplantation could eventually provide an additional source of kidneys for patients with kidney failure and reduce dependence on the limited supply of human donor organs.
