One year after becoming one of the first individuals to receive a genetically modified pig kidney, Tim Andrews has now undergone a successful human kidney transplant. This milestone makes Andrews the first known person to transition from a pig kidney to a human organ, marking a significant advancement in the field of xenotransplantation.
“I’m the first one that 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 shared from his hospital room. His journey from a groundbreaking procedure to a more conventional transplant underscores the potential of animal organs in bridging the gap for patients awaiting human donors.
The Promise of Xenotransplantation
Xenotransplantation, the process of transplanting organs from one species to another, has been heralded as a potential solution to the chronic shortage of human organ donors. In the United States alone, over 100,000 individuals are on the organ transplant waiting list, with kidneys in highest demand. This shortage has prompted researchers to explore alternatives, such as genetically modified pig organs, which are engineered to reduce rejection risks and size incompatibilities.
Dr. Leonardo Riella, medical director of kidney transplantation at Mass General Brigham and Andrews’ physician, emphasized the burden dialysis places on patients. “Dialysis is not able to reproduce what the body needs in terms of clearing the waste,” Riella explained. “It has a huge burden on the patient, both in their quality of life but most importantly on their health.”
From Experimentation to Reality
Andrews’ journey began with a pig kidney transplant on January 25, 2025, which allowed him to live without dialysis for 271 days—a record at the time. Despite the eventual rejection of the pig kidney, the procedure demonstrated the potential of xenotransplantation as a temporary solution for patients with end-stage renal disease.
Riella noted that even as a “bridge,” xenotransplantation offers significant benefits over dialysis. “Even if it is a bridge,” he said, “it would be better than [Tim] just staying on dialysis.”
“The five-year survival rate for patients on dialysis hovers around 40%.”
Advancements and Challenges
The path to Andrews’ human kidney transplant was not without its challenges. After the pig kidney, affectionately named Wilma, began to show signs of rejection, Andrews returned to dialysis. However, the experience provided valuable insights for future xenotransplant patients.
Mike Curtis, president and CEO of eGenesis, the company that provided the donor pig, explained the slow rejection process. “We just could not figure out how to push it back,” Curtis said. Research into Andrews’ case has since helped identify factors contributing to the rejection, potentially improving outcomes for future recipients.
A Vision for the Future
While xenotransplantation is still in its experimental stages, experts like Dr. Robert Montgomery, director of the NYU Langone Transplant Institute, believe it holds promise as a long-term solution. “As this gets better and xenografts last longer, it will be a destination,” Montgomery stated, envisioning a future where patients cycle through xenografts and allografts throughout their lifetimes.
For Andrews, the journey has been transformative. “If I didn’t take Wilma, I’d have been dead by now. I wasn’t gonna make it another year,” he reflected. Now, with a human kidney, he looks forward to a future where he can advocate for organ donation and share his story.
“People need to step up and help,” Andrews urged, highlighting the importance of organ donors.
In a heartfelt message to the family of his human donor, Andrews expressed his gratitude. “I grieve with you. It’s got to tear you apart, but I’m here to tell you, the donation of a kidney has saved my life, and you have given hope to millions. Your family member is a hero,” he said.
As Andrews prepares to return home to New Hampshire, his experience serves as a beacon of hope for the future of organ transplantation, offering a glimpse into the potential of xenotransplantation to save lives and alleviate the organ shortage crisis.
