Gene-edited pig kidney bridges patient to human transplant

For 271 days, Tim Andrews did not need dialysis. Then, in January 2026, after his gene-edited pig kidney was removed and he had spent months back on dialysis, he received a deceased-donor human kidney. The sequence, detailed in a Mass General Brigham paper in The Lancet, is the first documented bridge from a porcine kidney to a human transplant.

Xenotransplantation—the transfer of an organ from another species into a human—is being pursued because there are not enough human kidneys for everyone who needs one. Leonardo Riella, a lead author from Mass General Brigham’s Center for Transplantation Sciences and Division of Nephrology, describes the initial goal as a bridge that could keep patients off dialysis while they wait. A pig kidney might eventually become a long-term treatment, but the researchers say that would require evidence of safety and durability.

The scale of Andrews’s case becomes clearer against what came before. The first porcine kidney xenotransplant in a living human took place at Massachusetts General Hospital in 2024; that patient survived 52 days before dying from cardiac causes unrelated to the transplant. No earlier study had documented a xenograft surviving beyond two months or successfully carrying a patient to a human organ.

Andrews’s kidney functioned immediately. Doctors monitored kidney function, rejection, antibody development and possible pig-to-human infection; an early episode of T-cell-mediated rejection resolved with treatment, and no pig pathogen transmission was detected. After approximately six months, immunosuppression was reduced during an infection. The graft then developed microvascular injury—damage involving the organ’s smallest blood vessels—and inflammation that progressed to organ failure. The human kidney worked immediately after transplantation, with no evidence of sensitization during follow-up. Andrews received the pig kidney under a U.S. Food and Drug Administration Expanded Access Investigational New Drug application.

For patients with end-stage kidney disease, the concrete benefit is a possible stretch without dialysis while a human donor is sought—a bridge, not yet a proven permanent replacement. Andrews’s kidney eventually failed, but the late injury highlights areas for improvement in immunosuppressive treatment, donor genetic engineering and monitoring. STAT reports that two recipients have now gone on to receive human organs, turning a feared question about future human transplantation into an early clinical result rather than a theoretical one.