Pig Kidney Transplant Survives 271 Days in a Human Body, Raising New Hopes

When Tim Andrews walked into Massachusetts General Hospital in January 2025, he was 66, tired of endless dialysis sessions, and staring at a waiting‑list that could take up to seven years. He had end‑stage kidney disease caused by type‑2 diabetes, and the prospect of spending the rest of his life attached to a machine felt, in his own words, "depressing."

Enter a very different kind of donor: a Yucatan miniature pig that had been tweaked at the DNA level a staggering 69 times. Scientists at the Center for Transplantation Sciences engineered the animal so its organs would look less foreign to the human immune system, swapping out pig proteins that trigger attacks and adding bits of human DNA as a sort of camouflage. The goal was to create a kidney that could sit inside a person without being immediately rejected.

On January 25, 2025, surgeons Dr. Tatsuo Kawai and Dr. Leonardo Riella connected the pig kidney to Andrews’ blood vessels. The organ started filtering blood right away, giving him a taste of life without dialysis. "It felt like a light at the end of a very long tunnel," Andrews later recalled, his voice cracking with relief.

For 271 days—just shy of nine months—the transplanted kidney did its job. It wasn’t flawless; early on, the medical team spotted hints of immune activity and tweaked his medication. Still, the organ performed well enough that Andrews could ditch the dialysis machine for a good stretch of time.

Unfortunately, around the six‑month mark the kidney’s blood vessels began to show damage, inflammation set in, and the organ gradually lost function. There were no obvious antibodies attacking it, and researchers are still puzzling over the exact cause. In October 2025 the kidney was removed, and Andrews returned to dialysis for another 82 days while waiting for a human donor.

In January 2026 a conventional human kidney arrived, and it has been working without a hitch. "We are in a crisis of organ scarcity," Dr. Riella told reporters. "Xenotransplantation could become a bridge for patients like Tim, buying them precious time and perhaps even sparing them dialysis altogether."

In the United States roughly 100,000 people await a kidney each year, yet only about 25,000 transplants are performed. The UK faces a similar backlog, with over 7,000 on the list. Pigs are attractive candidates for xenotransplantation because their organs are similar in size to ours and they breed quickly, but the science still wrestles with immune rejection, viral safety, and long‑term durability.

Andrews’ experience underscores both the promise and the remaining challenges of this emerging field. As researchers fine‑tune genetic edits and immunosuppressive regimens, the dream of turning pig organs into viable, life‑saving bridges may move from headline news to everyday medical practice.