Pig kidney keeps a man alive nine months, then a human organ takes over

Timothy Andrews, 66, received a kidney from a Yucatan miniature pig named Wilma on 25 January 2025 at Mass General Brigham in Boston. The organ worked for 271 days. When its function declined in October 2025 it was removed and he went back on dialysis. In January 2026 he received a kidney from a deceased human donor. A paper in The Lancet on 3 September 2026 records the sequence as the first published case in which a pig kidney served as a bridge to a human transplant.

The pig organ was produced by eGenesis of Cambridge, Massachusetts, using CRISPR edits intended to reduce the human immune attack on pig tissue. Andrews had kidney failure and no realistic wait for a matched human organ. He later said that if he was going to die he might as well join the experiment. The pig kidney made urine and cleared waste around the clock. His diet improved. He put on muscle. "It gave me life," he said.

Dr Leonardo Riella of the Center for Transplantation Sciences at Mass General Brigham has described the organ shortage as the central crisis in the field. Average waits for a human kidney run three to five years and longer for some blood types. Five patients at Mass General Brigham have received eGenesis pig kidneys under an FDA expanded-access pathway for people with no other option. Three, including Andrews, lived with the organs for more than eight months. One patient died of a cardiac event soon after surgery. One was transplanted only in June 2026.

eGenesis said on 3 September that a second man has also received a human kidney after eight months with a pig organ, and that a woman transplanted at Massachusetts General Hospital on 22 November 2025 still had a functioning pig kidney at 285 days, a new duration record. Science magazine noted that the previous long mark for any nonhuman kidney in a person was 274 days, set in 1964 when Edith Parker lived with a chimpanzee kidney.

Richard Slayman, the first living recipient of a gene-edited pig kidney at Mass General in 2024, died about two months later of a cardiac event. The team used that case to argue the FDA into a wider programme. Later patients receive an implantable loop recorder to watch heart rhythm for four to five years. Subsequent recipients have not shown the same arrhythmias, Riella has said, which points back to Slayman's own heart rather than to the pig organ as the cause.

The Lancet paper does not claim that pig kidneys are ready to replace human ones for decades. It claims something narrower and more useful for the waitlist: a gene-edited pig organ can keep a person off dialysis long enough to reach a human donor, and a later human graft can function after that interval. Dr Nahel Elias Curtis, quoted with the team, said they had not known at the start whether a pig kidney would compromise a later human one. So far they see no such penalty.

eGenesis and academic partners are moving from single-patient access into trials that will test pig kidneys in patients over 50 for up to 24 weeks. The practical limit is still unknown. Andrews's 271 days, the unnamed woman's 285 days, and the second bridge to a human organ are three data points, not a standard of care. They are also the first numbers that make the waitlist look less like a closed list and more like a sequence that can include an animal organ in the middle.