Key Takeaway:
- Pig Kidney Transplant: A genetically modified pig kidney helped Tim Andrews stay off dialysis while awaiting a human kidney.
- Proof of concept: The case shows xenotransplantation could serve as a temporary bridge for patients facing long waits for donor organs.
- Remaining challenges: Immune rejection and other complications caused the pig kidney to fail, highlighting the need for further research.
Tim Andrews received a genetically modified pig kidney in January 2025 and, after 271 dialysis-free days, received a human kidney in January 2026, offering new evidence that animal organs could bridge the wait for scarce human donations.
Pig Kidney Buys Time For Human Organ
Andrews, who had end-stage kidney disease, received the pig kidney at Massachusetts General Hospital under an expanded-access U.S. Food and Drug Administration program. The Pig Kidney Transplant involved a genetically edited organ that functioned immediately and allowed him to avoid dialysis while he waited for a human donor.
The case, detailed in a study published in The Lancet, is the first reported transition from a pig kidney transplant to a human kidney transplant. Researchers said it also marks the longest dialysis-free survival reported after a pig kidney transplant in a living person.
“The organ shortage is the greatest crisis we have right now in transplantation,” said Leonardo Riella, the study’s lead author and a Mass General Brigham transplant physician. “We simply don’t have enough human organs to transplant in a timely manner.”
Andrews received the pig kidney after years of declining health and dialysis. His rare blood type also made finding a compatible human kidney more difficult, according to reports on his case.
Researchers Track Rejection And Organ Failure
The Pig Kidney Transplant continued functioning for months, but Andrews experienced an early episode of immune rejection that was treated. Later, after his immunosuppressive treatment was reduced because of an infection, the kidney developed blood-vessel damage and inflammation that eventually caused the organ to fail.
After 271 days, doctors removed the pig kidney and Andrews briefly returned to dialysis. He then received a deceased-donor human kidney in January, which began functioning immediately, with no evidence that the earlier pig transplant had made him more difficult to match with a human donor.
The outcome does not establish that pig kidneys can replace human kidneys permanently. Researchers said the case instead provides early evidence for using genetically modified animal organs as a temporary “bridge” for patients who are waiting for a human transplant.
Scientists See Potential In Xenotransplantation
The approach, known as xenotransplantation, involves transplanting organs between different species. Genetic engineering is being used to modify pig organs to reduce immune rejection and address other biological barriers.
Riella said the initial goal of a Pig Kidney Transplant could be to use pig kidneys to keep patients off dialysis while they await human organs. “Our vision is that xenotransplantation could help address this gap,” he said.
The researchers cautioned that further studies are needed to determine how reliably the organs can function and how to prevent complications. The findings also point to areas for improving genetic engineering, immune-suppressing treatments and monitoring after transplantation.
For Andrews, the experimental kidney provided time until a human organ became available. His case gives researchers a new path to investigate as they seek ways to reduce the consequences of the persistent shortage of donated kidneys.
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