Tim Andrews, 67, has made medical history by becoming the first person in the world to receive a human kidney after previously living with a genetically modified pig kidney. A year ago, Andrews was among a select group of patients to undergo an experimental xenotransplant at Mass General Brigham Hospital, designed to keep patients alive while awaiting a human organ.
“I’m the first one who went across the bridge… I’m the only person in the world that’s ever had a pig kidney and then had a human kidney after it,” Andrews told CNN.
The patient, who has diabetes and end-stage kidney disease, initially received the pig kidney on January 25, 2025, and lived with it for a record 271 days before his body rejected the organ, necessitating its removal in October.
The transition back to dialysis was difficult. “I cried,” Andrews recalled. “I didn’t expect to make it through the year.” Dialysis, which he underwent three times per week for up to six hours at a time, is physically and emotionally taxing, performing only a fraction of what healthy kidneys do naturally. Six months after starting dialysis, Andrews suffered a heart attack, illustrating the strain of long-term treatment.
On January 12, Andrews received life-changing news: a human kidney, a near-perfect match, had been identified. Surgery was performed the next morning, taking about three hours, and Andrews now anticipates returning home to New Hampshire. His new immunosuppressant regimen is roughly a third of the dosage required during his xenotransplant.
A Bridge to Life
Xenotransplantation the transplant of organs from one species into another has long been seen as a potential solution to the global organ shortage. In the United States alone, more than 100,000 people are on the organ waitlist, with around 80% requiring kidneys. Only the sickest patients are listed, leaving the majority of those with end-stage renal disease reliant on dialysis.
“Even if it is a bridge, it would be better than [Tim] just staying on dialysis,” said Dr. Leonardo Riella, medical director of kidney transplantation at Mass General Brigham and Andrews’ physician. The pig kidney, genetically modified to reduce rejection risk, allowed Andrews to live a relatively normal life for nine months. “I was clear… I wasn’t tired or anything. All of a sudden I had energy,” he said, recalling the relief from dialysis fatigue.
Despite the initial success, Andrews’ pig kidney affectionately named Wilma ultimately began to show signs of rejection and he developed two infections. “There was some damage to the filters of the kidney that, unfortunately, were not reversible,” Riella explained, prompting its removal.
Hope for the Future
Andrews sees his journey as a milestone not just for himself but for patients worldwide. “This will do something for humanity,” he said. Xenotransplants could serve as a vital bridge for those awaiting human organs, providing critical time and improved quality of life.
With the successful human kidney transplant, Andrews now represents a proof-of-concept for combining xenotransplantation and traditional organ transplantation to save lives a potential blueprint for addressing the ongoing organ shortage crisis.
