Man receives human kidney transplant after surviving 271 days with gene-edited pig organ

A gene-edited pig kidney kept a 66-year-old man with end-stage kidney disease off dialysis for 271 days before doctors replaced it with a human organ.

Tim Andrews had no suitable living donor and faced a long expected wait for a deceased-donor kidney when he underwent the porcine transplant in 2025. Doctors at Massachusetts General Hospital later performed a human kidney transplant, according to a Mass General Brigham study published in The Lancet.

The pig kidney initially showed signs of rejection. Doctors controlled those symptoms with immunosuppressive treatment, which remained effective for six months. A bacterial infection later forced them to reduce the immunosuppression. Researchers said the infection was unrelated to the transplant and that the pig transmitted no pathogen.

After 271 days, doctors removed the kidney and Andrews returned to dialysis for 82 days. He then received a human kidney almost a year after the porcine transplant. The human transplant succeeded, and monitoring found no negative effect from the pig organ on his ability to tolerate the new kidney.

The case adds to research into xenotransplantation, which seeks to address organ shortages by transplanting animal organs into humans. Scientists have genetically modified pigs because their organs are similar in size to human organs, while reducing the risk that the human immune system will recognize them as foreign and attack them.

Researchers said Andrews's experience shows that a pig kidney could serve as a temporary bridge until a human organ becomes available.