Genetically modified pig kidney functioned in patient for a record nine months
In the United States, a kidney from a genetically modified pig functioned in the body of 66-year-old Tim Andrews, who had end-stage kidney failure, for 271 days — a record nine months. The organ allowed the patient to avoid dialysis and later became a temporary solution until a human kidney transplant, The Guardian reports.
Transplant in Massachusetts
The operation was performed in January 2025 at Massachusetts General Hospital. The kidney was transplanted from a Yucatan minipig named Wilma. Before the transplant, 69 changes were made to the animal’s genome. Some were intended to reduce risks associated with viruses that could potentially be dangerous to humans, while others were meant to make the organ more compatible with the recipient’s immune system and reduce the likelihood of rejection.
Andrews, who lives in New Hampshire, had end-stage kidney failure caused by type 2 diabetes. His probability of receiving a human kidney within five years was estimated at 9%, while the risk of dying or being removed from the waiting list exceeded 40%.
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Transition to a human kidney
About six months after the operation, damage appeared in the blood vessels of the transplanted pig kidney, which later led to organ failure. The kidney was removed nine months after the transplant. After several months on dialysis, Andrews received a kidney from a deceased human donor; during six months of follow-up, it functioned well.
Researchers found no new antibodies against human tissues in the patient, indicating no signs that the pig kidney complicated the subsequent transplant. No pig viruses or other pathogens were detected at any point. The results of this case were published in the medical journal The Lancet.
The Mass General Brigham team said this was the first documented case in which a pig kidney served as a temporary bridge to transplantation of a human organ. At the same time, doctors stressed that this involved only one patient without a comparison group, and that the result requires further clinical research.
