Mass General team performs second xenotransplant of genetically edited pig kidney

Massachusetts General Hospital in Boston performed its second successful transplant of a genetically edited pig kidney into a living recipient in January 2025. MGH surgeons performed the world’s first such transplant in March 2024. Xenotransplantation, the term for the transplantation of organs from one species to another, is an experimental treatment being researched as a “potential solution” to the global organ shortage.

The patient in the second transplantation surgery, 66-year-old Tim Andrews, was discharged from the hospital about a week after the transplant and is doing well. Andrews had been on dialysis for more than two years due to end-stage kidney disease. His blood type is group O, and people with O positive and O negative blood types typically wait five to 10 years for a donor organ, compared to three to five years for most patients.

Advancements in the field of transplantation have helped address a worldwide organ shortage. According to the Health Resources & Services Administration, more than 103,000 people in the U.S. await an organ for transplant, and 17 people die each day waiting for an organ. MGH received approval from the Food and Drug Administration to proceed with this surgery and plans to perform two more xenotransplants in 2025.

Andrews said he awoke from the transplant surgery feeling “reenergized and revitalized,” noting that “the magnitude of what these doctors and nurses accomplished is unbelievable.”

Leonardo Riella, M.D., medical director for kidney transplantation at MGH and Andrews’ nephrologist, observed that the milestone operation “reminds us of the transformative potential” of xenotransplantation. “We remain committed to learning from this experience to make it a safe, viable option for every patient in need. Together, we are working toward a future where no one has to die waiting for a kidney,” Riella said.

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