Pig kidney kept patient off dialysis for 271 days before human transplant

Doctors in Boston have described the first case in which a genetically edited pig kidney carried a patient through to a transplant from a human donor, in a report published in the medical journal The Lancet on 3 September 2026.

The patient, Tim Andrews, was 66 and had kidney failure when he received the pig organ at Massachusetts General Hospital on 25 January 2025. He had been allowed to undergo the procedure under the US Food and Drug Administration’s expanded-access rules, which permit experimental treatments for seriously ill patients outside a formal clinical trial. According to the hospital group Mass General Brigham, the kidney worked immediately and he went 271 days without dialysis, the machine-based blood filtering on which people with failed kidneys otherwise depend.

The hospital described that as the longest dialysis-free survival after a pig kidney transplant in a living person. Its first such patient, in 2024, lived for 52 days and died of cardiac causes that the hospital said were unrelated to the transplant.

How the pig kidney failed

The report is as much an account of a failure as of a success. An early episode of rejection driven by the immune system’s T cells was treated and resolved. No transmission of pig pathogens was detected, a long-standing safety concern with animal organs.

About six months after the operation, however, Andrews developed an infection and his doctors reduced the drugs suppressing his immune system. The pig kidney then developed injury and inflammation in its small blood vessels, which progressed to organ failure. In January 2026 he received a kidney from a deceased human donor. That organ worked at once, the hospital said.

One finding bears on whether pig organs can be used as a stopgap. Exposure to foreign tissue can prime a patient’s immune system in ways that make a later transplant harder to match, a process called sensitisation. The authors reported no evidence of it during follow-up after the human transplant. They wrote that the case shows a pig kidney can safely support kidney function “while also serving as a bridge” to a later transplant with a human organ.

They also said the blood-vessel injury had implications for how immune-suppressing drugs are managed, how donor pigs are genetically engineered and how recipients are monitored in future studies.

Limits of a single case

The paper describes one patient. It cannot show how often a pig kidney would last this long, how often it would fail in the same way, or whether other recipients would avoid sensitisation. Those are questions for controlled trials with many participants.

Leonardo Riella, the report’s lead author, placed the result in the context of supply. “The organ shortage is the greatest crisis we have right now in transplantation,” he said in the hospital’s statement. More than 100,000 people are on the transplant waiting list in the United States, most of them waiting for a kidney, NBC News reported.

NBC quoted Riella as saying that pig organs could first be used “as a bridge to get patients off dialysis while they wait for a human donor kidney”, and might later become a lasting treatment in their own right if long-term safety and durability are established. That has not yet been shown.

“The patients are the true pioneers here,” he said in the statement. “Without their trust and courage, we would not be able to do what we do.”

Andrews’s 271 days may already have been passed. In the week the paper appeared, the magazine Wired reported that a woman who received a pig kidney at the same hospital on 22 November 2025 had reached 285 days with the organ functioning and without dialysis. That figure came from eGenesis, the Massachusetts biotechnology company that edited the pig’s genes, and has not been described in a published paper.