The Pig Kidney That Kept a Man Alive Without Dialysis for 271 Days

In January 2025, 66-year-old Tim Andrews received a kidney from a pig — genetically edited so his human immune system would accept it. He lived with that pig kidney for 271 days without a single dialysis session, then became the first person in history to transition from a pig-kidney transplant to a human-kidney transplant in January 2026.

The case, detailed in a paper published September 3, 2026 in The Lancet by researchers at Mass General Brigham in Boston, sets the record for the longest dialysis-free survival after a pig-kidney transplant in a living person.

A Bridge, Not a Destination — Yet

The vision, according to lead author Dr. Leonardo Riella of Mass General Brigham's Center for Transplantation Sciences, is to use genetically edited pig kidneys as a "bridge" therapy: keeping patients with end-stage kidney disease off dialysis while they wait for a human donor organ. The organ shortage, he notes, is the greatest crisis in transplantation — there simply aren't enough human kidneys to go around.

Andrews' case proves the bridge concept works. His pig kidney started working the moment it was implanted. He experienced one mild rejection episode, which treatment resolved, and tests found no sign of any pig virus jumping to him.

Xenotransplant Milestones: How We Got Here

Why 271 Days Changes Everything

Before Andrews, no published study had documented pig-kidney survival beyond about two months in a living recipient. Stretching that to nine months — with no dialysis, no pig virus transmission, and a successful handoff to a human organ — moves xenotransplantation from experimental curiosity toward clinical reality.

What's Next for Xenotransplantation

Andrews' case answered the biggest open question — can a pig kidney keep a human alive and healthy for months? — but several hurdles remain before pig kidneys become routine:

• Long-term durability: 271 days is a record, but a human kidney transplant is expected to last 10–15 years. Researchers need to show pig kidneys can go the distance.
• Rejection management: Andrews had one mild rejection episode. The immune-suppression regimens still need refining for broader patient populations.
• Regulatory path: The U.S. FDA has allowed these procedures under compassionate-use and trial frameworks. Full clinical trials with dozens of patients are the next step, and several are already being planned.
• Scale: The gene-edited pigs come from specialized biotech firms. Scaling from a handful of experimental organs to thousands per year is an industrial challenge as much as a medical one.

The researchers' stated vision has two phases: first the bridge (pig kidney keeps you off dialysis while you wait), then the destination (the pig kidney is the transplant). Andrews proved phase one. Phase two is now the most exciting race in transplant medicine.

Thousands of people wait years for a kidney; many get sicker or die waiting. If pig kidneys can reliably buy patients nine months or more off dialysis, the organ shortage starts to look solvable. The researchers' next goal: making the pig kidney a permanent destination therapy, not just a bridge.