Genetically modified pig kidney supports patient 271 days before human transplant

September 7, 2026 at 06:15 PM2 min

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US surgeons transplanted a genetically modified pig kidney into a patient with end-stage kidney disease, and the organ functioned for 271 days without dialysis. The patient, Tim Andrews, later received a human kidney transplant in January 2026 and remained healthy after six months of follow-up. The case, reported in The Lancet, is the first documented successful transition from a pig kidney to a human donor organ.

Key Facts

The pig kidney carried 69 genetic modifications to improve compatibility and reduce rejection risk.
Tim Andrews lived 271 days without dialysis after the January 2025 transplant at Massachusetts General Hospital.
The patient received a human kidney transplant in January 2026 and had normal function at six-month follow-up.
No pig-derived viruses or pathogens were detected in the patient after the transplant.
The clinical case was published in The Lancet.

The Transplant

Tim Andrews, who had end-stage kidney disease from type 2 diabetes, received a genetically modified pig kidney in January 2025 at Massachusetts General Hospital. Doctors estimated his chance of receiving a human donor kidney within five years at only 9 percent, while the risk of death or removal from the transplant list exceeded 40 percent. The kidney came from a Yucatan miniature pig and was named 'Wilma' by the patient. The pig genome had 69 edits to enhance compatibility with the human body and reduce the risk of immune rejection. Part of the genetic editing aimed to lower the risk of viruses that could be transmitted from the animal to the human.

Bridge to Human Transplant

The pig kidney began working immediately after surgery, and Andrews lived 271 days without dialysis, returning to daily activities such as cooking, household chores, and long walks with his dog. About six months after the transplant, signs of damage appeared in the blood vessels of the pig kidney, and the organ began to fail after nine months. Doctors removed the pig kidney and returned the patient to dialysis. About 82 days after returning to dialysis, Andrews received a kidney from a deceased human donor in January 2026. At six-month follow-up, the new human kidney was functioning normally.

Clinical Significance

Testing showed the pig kidney did not cause the formation of new antibodies against human tissues, indicating the first transplant did not hinder the subsequent human kidney transplant. No pig-specific viruses or other pathogens were found in the patient. The pig kidney served as a temporary 'bridge' until a human donor was found, rather than as a permanent treatment. This is the first reported case in the world of a successful human kidney transplant after a pig kidney. Researchers caution that the result from one patient is insufficient to fully prove the safety and effectiveness of the method, and clinical trials are needed for wider use.