Gene-Edited Pig Kidney Keeps Patient Off Dialysis for 271 Days
A genetically modified Yucatan miniature pig kidney helped Tim Andrews, a U.S. patient with end-stage kidney disease, avoid dialysis for 271 days before doctors removed it after its function declined. He then received a deceased human donor kidney successfully.
The case is the first documented use of a genetically modified pig kidney as a temporary bridge to human transplantation. Researchers say it suggests a possible strategy for patients awaiting donor organs, but the approach remains experimental, with risks involving rejection, infection, durability and immunosuppression.
A genetically modified pig kidney has helped a U.S. patient with end-stage kidney disease remain free from dialysis for 271 days before he successfully received a human donor kidney.
The case involving Tim Andrews, treated by surgeons at Massachusetts General Hospital, is being described as a major milestone in xenotransplantation—the transplantation of organs between different species. Researchers say it is the first documented case in which a genetically modified pig kidney served as a temporary bridge to a subsequent human kidney transplant.
Andrews received the pig kidney on January 25, 2025. The organ came from a genetically modified Yucatan miniature pig. Scientists made multiple genetic changes to reduce the likelihood of immune rejection and improve the kidney’s compatibility with the human body.
The kidney functioned for 271 days, allowing Andrews to live without dialysis for roughly nine months. Doctors eventually removed the organ after its function declined. In January 2026, Andrews received a kidney from a deceased human donor.
According to Harvard Medical School, the subsequent human transplant was successful, and doctors found no evidence that the earlier pig-kidney transplant had caused immune sensitization that would prevent him from receiving a human organ.
The researchers say the result could point toward a new strategy for patients waiting for human donor organs. A genetically modified animal kidney could potentially provide temporary kidney function and allow some patients to avoid dialysis while they wait for a suitable human donor.
However, scientists caution that the approach remains experimental. A single successful case cannot establish long-term safety or effectiveness, and researchers still need to address immune rejection, infection risks, organ durability and the need for immunosuppressive treatment.
The development comes as medical researchers search for ways to address the shortage of human kidneys available for transplantation. Mass General Brigham has described xenotransplantation as a potential approach to expanding the future supply of transplantable organs.
The Andrews case provides important evidence that gene-edited animal organs may eventually have a role not only as replacements, but also as temporary bridges to human transplantation.
