After becoming the person who has lived the longest with a kidney donated from a pig, a 66-year-old man has received a human kidney, according to research published this week in The Lancet journal. His story shows a possible path forward for the tens of thousands of Americans waiting for kidney donations.
Last year, 27,574 kidney transplants were performed in the U.S., per the Health Resources & Services Administration. As of July 30, 95,492 people in the country were waiting for a kidney donation.
“The organ shortage is the greatest crisis we have right now in transplantation,” said Leonardo Riella, MD, PhD, of the Center for Transplantation Sciences and the Division of Nephrology at Mass General Brigham and lead author of the study, according to a press release from the hospital.
Overall, the Health Resources & Services Administration estimates that 12 people die each day waiting for an organ transplant. Kidneys are the most commonly needed organ for transplantation.
To work around the shortage, doctors have tried to treat patients with gene-edited pig kidneys. Animal transplants in humans are called xenotransplants. In addition to kidneys, doctors have also experimented with pig to human heart transplants, as explained by the University of Maryland School of Medicine.
“The world’s first porcine kidney xenotransplant to a living human recipient occurred in 2024 at Massachusetts General Hospital, with the patient surviving 52 days before death from cardiac causes unrelated to the transplant,” said Mass General Brigham. Most xenograft patients do not survive beyond two months.
Then came Tim Andrews, the 66-year-old who received a genetically edited pig kidney in January 2025. He lived dialysis-free with the pig transplant for a record-breaking 271 days (around nine months) before receiving a human kidney donation. Dialysis is a medical intervention that helps the body filter waste and excess fluid from the blood when the kidneys are not working properly, the Cleveland Clinic explained.
“We know that the best treatment option for patients with end-stage kidney disease who have developed renal failure is transplantation, but we simply don’t have enough human organs to transplant in a timely manner,” said Riella. “Our vision is that xenotransplantation could help address this gap – initially as a bridge to get patients off dialysis while they wait for a human donor kidney, and potentially, as we establish long-term safety and durability, as a destination therapy in its own right.”
While scientists have found success using pig collagen to treat blindness, Audacy reported back in 2024 that all humans who had received actual pig organs had died. This new development presents a hopeful outlook for xenotransplantation. However, Andrews’ experience did come with some challenges.
He received a genetically engineered pig kidney under a U.S. Food and Drug Administration Expanded Access Investigational New Drug application and was monitored for kidney function, rejection, antibody development, and potential pig-to-human infection. Things got off to a good start after the operation – the kidney immediately functioned.
“Kidneys perform important functions that keep the body in balance, such as filtering blood, regulating blood pressure, and removing waste,” according to the National Kidney Foundation.
Andrews had an “early episode of T-cell-mediated rejection resolved with treatment,” and no pig pathogen transmission was detected. Around six months after the transplant, “immunosuppression was reduced in the setting of infection,” and “the xenotransplant subsequently developed microvascular injury and inflammation that progressed to organ failure.”
Fortunately, Andrews was able to receive a deceased-donor human kidney at that point. Mass General Brigham said there was “immediate graft function and no evidence of sensitization during follow-up.”
“The findings illustrate both the promise and areas for improvement for xenotransplants as a bridge for patients awaiting human kidneys,” said the hospital. “Importantly, the microvascular injury to the porcine kidney has implications in the development of immunosuppressive strategies, donor genetic engineering, and monitoring in future clinical transplantation studies.”
