Genetically modified pig kidney keeps man alive for record nine months before human transplant

For nine months, a kidney from a genetically modified pig named Wilma kept Tim Andrews alive without dialysis. The transplant became the first documented case of a pig kidney serving as a temporary bridge to a human kidney.

Andrews, 66, had end-stage kidney disease caused by type 2 diabetes. Before the operation, doctors estimated that he had only a 9% chance of receiving a human kidney within five years, while placing his risk of dying or being removed from the waiting list above 40%. The human transplant eventually came from a deceased donor after the pig kidney began to fail.

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miracle

The kidney came from a Yucatan miniature pig whose genome had undergone 69 edits. Some changes aimed to block viruses that could threaten humans. Others were designed to make the organ more compatible with the human immune system and reduce rejection. Surgeons at Massachusetts General Hospital carried out the transplant on Jan. 25, 2025.

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I was alive, and I hadn’t been in a long time.

The kidney worked for 271 days, the longest period recorded for dialysis-free survival after pig kidney xenotransplantation in a living human. Earlier efforts had not documented survival beyond two months, and a 2024 transplant ended after 52 days when the recipient died from unrelated heart problems.

The details, published in The Lancet, add to hopes that animal organs could help address the shortage of human kidneys. Andrews said the transplant was a “miracle.” He said it allowed him to cook, vacuum and take long walks with his dog, Cupcake. “I was alive, and I hadn’t been in a long time,” he said. Dr Leonardo Riella of Mass General Brigham called the shortage of organs “the greatest crisis we have right now in transplantation.”

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The organ shortage is the greatest crisis we have right now in transplantation.