A genetically modified pig kidney has been successfully transplanted into a second recipient.
Sixty-six-year-old Tim Andrews, a Concord, New Hampshire resident with end-stage kidney disease, received the transplant at Massachusetts General Hospital on January 25th. He had been on dialysis for over two years. This procedure is part of a three-patient FDA-approved study.
Andrews was discharged on February 1st and is undergoing follow-up care in the Boston area before returning home. The transplanted kidney is functioning normally and producing urine.
This procedure offers hope for addressing the critical organ shortage in the U.S. Andrews faced a less than 10% chance of receiving a human kidney within five years and a nearly 50% chance of removal from the transplant waiting list due to his declining health. His dialysis significantly limited his activities, and he suffered a heart attack in 2023. In 2023, only slightly over 27,000 transplants were performed, highlighting the substantial gap between organ demand and supply that xenotransplantation could help bridge.
How pig kidneys can work in humans
Xenotransplantation faces the challenge of the body rejecting foreign tissue. Andrews’ transplant was made possible by advancements in cloning and CRISPR gene editing. eGenesis, the company that produced the kidney, removed three key pig proteins, added seven human genes to enhance compatibility, and deactivated harmful pig viruses.
This builds upon the March 2024 transplant of a pig kidney into Richard Slayman. While Slayman initially recovered well, he passed away two months later from unrelated causes.
According to Michael Curtis, CEO of eGenesis, Andrews received the same genetically modified kidney as Slayman. The success with Slayman provided sufficient data to warrant a second attempt.
A key difference from Slayman’s case is that Andrews had less severe end-stage kidney disease. He had been on dialysis for only two years and possessed a stronger cardiovascular system compared to Slayman, who had been on dialysis for eight years and had a history of kidney transplant and heart disease. This approach may optimize outcomes and provide valuable insights into ideal transplant candidates.
Dr. Leonardo Riella, Massachusetts General Hospital’s medical director for kidney transplantation, stated at a press briefing that xenotransplantation offers a superior solution to dialysis and represents a pivotal advancement in overcoming organ shortages.
Similar to Slayman, Andrews received an experimental immunosuppressant drug from Eledon Pharmaceuticals to minimize rejection. This drug is currently undergoing trials in human kidney transplant settings.
Next step: clinical trials
eGenesis is not alone in developing pig organs for human transplantation. United Therapeutics received FDA approval for a large-scale trial involving pig kidneys, also modified for human compatibility, potentially involving 50 patients contingent on successful 12-week outcomes for the initial patients.
The positive results from Slayman and Andrews are prompting exploration into other potential animal organ transplants, including pig hearts. Encouraging results from baboons receiving genetically modified pig hearts—survival exceeding 500 days—suggest the possibility of using pig hearts as a permanent solution rather than a temporary bridge to human heart transplants, though further research is necessary.
Andrews’ medical team will closely monitor his progress, influencing the timing and continuation of the trial with the remaining two patients.
Dr. Riello noted Andrews’ significant improvement, contrasting his initial frail condition with his ability to leave the hospital unassisted upon discharge.
Dr. Riello emphasized that Andrews’ successful transplant signifies hope for millions suffering from kidney failure and represents progress towards establishing xenotransplantation as a viable solution for the organ shortage crisis.
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