A Record‑Breaking Bridge: 271 Days Without Dialysis Thanks to a Gene‑Edited Pig Kidney

When Tim Andrews, a 66‑year‑old from New Hampshire, learned that a kidney from a gene‑edited pig would be transplanted into his body, he was skeptical, hopeful, and a little terrified. The organ came from a tiny Yucatan miniature pig that scientists had tweaked at 69 specific genetic spots – changes meant to keep viruses at bay and to make his immune system less likely to attack the foreign tissue.

On the day of surgery at Mass General Brigham, the pig kidney was wired up to Tim’s bloodstream and, within minutes, started doing its job. No dialysis machines were needed. For the next nine months Tim could cook, take walks, and even tend to his garden – ordinary things that dialysis had robbed him of for years.

“I felt alive again,” Tim recalled, his voice cracking a bit. “I hadn’t felt that way in a long time.” The kidney acted like a temporary bridge, buying him precious time while he waited for a human donor organ.

But a bridge isn’t meant to be permanent. Around the six‑month mark, doctors noticed subtle changes in the tiny blood vessels of the pig kidney – a kind of micro‑inflammation that, over time, would erode its function. By day 271, the organ’s performance was waning, and the team decided to remove it.

Crucially, the removal was uncomplicated. Blood tests showed that Tim’s immune system hadn’t become sensitised to pig antigens – a major concern for any future transplant. Even more reassuring, no traces of porcine endogenous retroviruses or other pig‑derived pathogens were found in his blood.

After a short stint back on dialysis, a human kidney from a deceased donor arrived. Surgeons placed the new organ, and within days it was churning out waste as expected. Today, the human kidney is still functioning well, and Tim has returned to a life that feels, for the first time in years, genuinely his own.

This case, detailed in The Lancet, is more than just a medical curiosity. It proves that a genetically modified animal organ can safely serve as a temporary “bridge” for a living patient, without triggering the immune backlash that has plagued earlier xenotransplant attempts. It also offers a glimmer of hope for the millions worldwide stuck on endless dialysis lists, waiting for a donor organ that may never come.

Experts caution that this is only the first step. Larger clinical trials are needed to fine‑tune immunosuppression protocols, improve the durability of the animal organ, and ensure long‑term safety. Still, the success story of Tim Andrews provides a tangible proof‑of‑concept that could reshape how we think about organ shortages in the years ahead.