In a significant development in transplant medicine, a genetically modified pig kidney has helped keep a patient alive without dialysis until he could receive a human donor kidney.
Tim Andrews, 66, became the first known patient to receive a human kidney after previously living with a genetically modified pig kidney. His case offers early evidence that animal organs could one day serve as a temporary bridge for patients waiting for a human transplant.
Pig kidney worked for 271 days
Andrews received the genetically modified pig kidney in January 2025 after severe kidney disease had left him dependent on dialysis.
The transplanted organ began functioning immediately and allowed him to remain free from dialysis for 271 days. During that period, doctors said his health improved, including his appetite and muscle strength.
The kidney eventually developed blood-vessel damage and inflammation, leading to organ failure. Andrews briefly returned to dialysis before receiving a kidney from a deceased human donor in January 2026.
Human transplant worked after pig kidney
One important question surrounding xenotransplantation was whether receiving an animal organ could make a later human transplant more difficult.
In Andrews’ case, the human kidney began functioning immediately, with doctors finding no evidence that the earlier pig transplant had made him more likely to reject the human organ. No pig pathogen transmission was detected during monitoring.
The finding provides encouragement for researchers exploring genetically modified animal organs as a way of helping patients survive while waiting for scarce human donor organs.
Breakthrough could help address organ shortage
Around 90,000 people in the United States are waiting for kidney transplants, while many patients die before receiving a suitable organ. Researchers believe pig kidneys could initially be used to keep seriously ill patients off dialysis while they wait for a human donor.
The experimental approach, known as xenotransplantation, involves genetically modifying pig organs to reduce immune rejection and address other risks.
Researchers caution that much more work is needed before the treatment can become routine. A larger clinical trial involving 33 patients is expected to begin next year.
For now, Andrews’ experience marks an important step towards a future in which a pig kidney could provide precious time to patients waiting for the human organ that may ultimately save their lives.