In a groundbreaking moment for transplant medicine, Massachusetts General Hospital (MGH) has concluded its second successful xenotransplantation of a genetically modified pig kidney into a human patient. Tim Andrews, a 67-year-old retired engineer from Concord, New Hampshire, became the longest-living recipient of such an organ, surviving 271 days before the kidney was surgically removed due to declining function, as reported by Becker’s.
Andrews received the transplant in January 2025 as part of a pilot study led by Mass General Brigham and biotech firm eGenesis. The pig kidney, engineered with 69 gene edits using CRISPR technology, was designed to reduce the risk of immune rejection and improve compatibility with the human body. The procedure offered Andrews a reprieve from dialysis, allowing him to regain energy and participate in life events, including throwing the first pitch at a Boston Red Sox game in June.
His case follows three previous attempts in the U.S., two of which ended in patient deaths and one in organ rejection after 130 days. Andrews’ survival set a new benchmark for xenotransplantation, surpassing all prior durations and offering valuable insights into the viability of animal-to-human organ transplants.
Despite the eventual removal of the organ on October 23, Andrews remains optimistic and continues to advocate for organ donation. He has resumed dialysis and is back on the waitlist for a human kidney. Due to the effects of the experimental treatment, he is not eligible for another pig kidney transplant.
Mass General Brigham has announced plans to continue its xenotransplantation research, with a third genetically edited pig kidney transplant scheduled for later this year. The FDA has also approved broader clinical trials, potentially involving over 30 patients across multiple transplant centers.
Andrews’ journey, while medically complex, represents a significant step forward in addressing the global organ shortage. With over 100,000 people in the U.S. awaiting kidney transplants and thousands dying each year before receiving one, xenotransplantation could become a transformative solution for end-stage organ failure.
