Tim Andrews, a recipient of a genetically modified pig kidney a year ago, has now become the first person in the world to receive a subsequent human kidney. Andrews, who has diabetes and end-stage kidney disease, underwent the pig kidney transplant on January 25, 2025. He lived with the organ for 271 days before it was rejected and removed in October, leading to his return to dialysis.
On January 12, a suitable human kidney match was identified, and Andrews underwent transplant surgery the following day. He is expected to be discharged to his home in New Hampshire soon after the procedure.
Xenotransplantation, the transplantation of organs between different species, is being explored as a potential solution to the shortage of human organ donors. The pig organs used in these procedures are genetically modified to mitigate rejection and manage size.
In the U.S., over 100,000 individuals are awaiting organ transplants, with approximately 80% requiring kidneys. However, only a fraction of patients with end-stage renal disease are on the waitlist. Of the more than 800,000 people with kidney failure, nearly 70% rely on dialysis. Dialysis attempts to replicate the kidneys' continuous function within a few hours weekly, and the five-year survival rate for patients on dialysis is around 40%.
Dr. Leonardo Riella, medical director of kidney transplantation at Mass General Brigham Hospital and Andrews' physician, stated that dialysis places a significant burden on patients' quality of life and health. Andrews experienced a heart attack six months after beginning dialysis and reported physical and emotional exhaustion.
To prepare Andrews for the human transplant, his medical team tested for new antibodies and found none that could react with the new organ. The recent transplant surgery lasted approximately three hours, and his current immunosuppressant regimen is less intensive than what he required with the pig kidney.
Andrews' pig kidney kept him off dialysis for nine months. Over that period, the organ exhibited signs of rejection, including damage to the kidney's filters that was ultimately irreversible, necessitating its removal. Insights gathered from biopsies and research into Andrews' experience and the pig kidney are expected to aid in identifying factors contributing to rejection and refining future immunosuppression protocols for xenotransplant patients.
Mike Curtis, president and CEO of eGenesis, which provided the donor pig, indicated that the slow rejection process was observed for months, providing data for further research. Since Andrews' initial surgery in January 2025, Mass General and eGenesis have conducted two additional xenotransplants and plan to initiate a clinical trial in the near future.
Dr. Riella views xenotransplantation as a more effective treatment for maintaining kidney function compared to dialysis, even if it serves as a temporary measure. Dr. Robert Montgomery, director of the NYU Langone Transplant Institute, who was not involved in Andrews' care but is a leader in xenotransplantation, believes xenotransplantation will become a viable, long-term solution within five years. He anticipates that patients with renal failure may utilize both xenografts and allografts throughout their lives.
Andrews expressed conviction that the pig kidney prolonged his life, providing him a pathway to the human transplant. He plans to share his story and advocate for organ donation. In a social media post, Andrews thanked the family of his unidentified donor, acknowledging their act of donation as life-saving and offering hope.