Gene-Edited Pig Kidney Keeps US Patient Off Dialysis for 271 Days
A genetically modified pig kidney has functioned inside a US patient for 271 days, in what doctors describe as a major step forward for xenotransplantation and a potential new way to address the shortage of human donor organs.
The patient, Tim Andrews, was 66 when doctors at Massachusetts General Hospital transplanted the kidney from a genetically engineered Yucatan miniature pig in January 2025.
The experimental organ immediately began filtering his blood and allowed Andrews to remain free from dialysis for nine months while he waited for a human donor kidney.
After 271 days, doctors removed the pig kidney when its function began to deteriorate. Andrews spent another 82 days on dialysis before receiving a human donor kidney in January 2026, which doctors say is functioning well.
Researchers say the case is particularly significant because it provides early evidence that a genetically engineered pig kidney could serve as a temporary bridge for patients waiting for a human transplant, potentially reducing the physical toll of prolonged dialysis.
The kidneys are genetically modified to make them more compatible with the human immune system and reduce the risk of rejection and pathogen transmission. Five patients have received the experimental kidneys through an FDA expanded-access programme, with three achieving more than eight months of sustained function without dialysis.
Dr Leonardo Riella of Massachusetts General Hospital says the shortage of donor organs remains one of transplantation’s biggest challenges, and xenotransplantation could eventually provide another option.
However, doctors stress that the procedure remains experimental. Larger clinical trials are needed to establish its long-term safety and effectiveness before pig kidneys can become a routine alternative to human organs.
