A genetically modified pig kidney kept a man with end-stage kidney failure off dialysis for nine months, a record duration that researchers say demonstrates the potential of animal-to-human transplants as a temporary measure while patients wait for human donor organs.
According to New Scientist, the patient was Tim Andrews, a 66-year-old man who opted for the procedure to avoid dialysis while awaiting a suitable human kidney. Leonardo Riella and colleagues at Mass General Brigham hospital in Boston performed the transplant in January 2025. The kidney came from a Yucatan miniature pig that had been genetically modified to improve compatibility with the human immune system, including the removal of certain sugars that trigger human antibodies and the addition of seven human genes.
The transplant was initially a success. Andrews came off dialysis and resumed normal life. He also received immunosuppression drugs to prevent his body from rejecting the organ.
At around the six-month mark, Andrews was admitted to the hospital with a methicillin-resistant Staphylococcus aureus infection, a type that most antibiotics cannot kill. Riella and his team reduced his immunosuppression drugs in response, but that decision led to damage in the kidney's blood vessels. The organ eventually failed and was removed 271 days after transplantation. "He had a kidney that lasted nine months, which is mind-blowing," said Riella.
Andrews returned to dialysis for about three months before receiving a human kidney in January 2026. This marked the first time a pig kidney had been used as a temporary bridge to a human transplant.
The case builds on a short but significant history of xenotransplantation. A pig heart was transplanted into a human for the first time in January 2022, but the recipient died several months later. A pig kidney was first transplanted into a living person in 2024, when Richard Slayman, 62, received the organ but died 52 days later from cardiac-related causes.
Michelle Willicombe at Imperial College London, who was not involved in the work, called the result significant. "I think it's incredible in terms of the science behind it and what they've achieved," she said.
Riella placed the achievement in a longer timeline. "Such transplants may allow patients to avoid going through dialysis, which is so important because it causes so much wear and tear to the body," he said. "Hopefully, maybe 15 years from now, pig kidneys will compete with a human kidney transplant, but you're not there yet."
The procedure remains experimental. Demand for donor kidneys far exceeds supply, and dialysis, while life-sustaining, takes a serious physical toll on patients over time. Researchers say pig kidneys could eventually serve not just as a bridge but as a permanent replacement, though that remains a longer-term goal.
