A patient with end-stage kidney disease who received a genetically edited pig kidney later successfully underwent a human kidney transplant, marking the first documented transition from a pig organ to a human donor kidney.

Tim Andrews, who was 66 when he received the pig kidney in January 2025, lived with the organ for 271 days without needing dialysis, according to researchers from Harvard Medical School and Massachusetts General Hospital.

The case, detailed in a study published on 3 September in The Lancet, represents the longest dialysis-free survival after a pig kidney xenotransplant in a living person and the first successful use of such a transplant as a temporary “bridge” to a human kidney.

The genetically engineered kidney began functioning immediately after transplantation. Andrews was monitored for kidney function, rejection, antibody development and possible transmission of pig pathogens.

Researchers said an early episode of T-cell-mediated rejection was successfully treated, while no pig pathogen transmission was detected.

After about six months, doctors reduced Andrews’ immunosuppressive medication because of an infection. The pig kidney later developed microvascular injury and inflammation that eventually led to organ failure.

Andrews temporarily returned to dialysis before receiving a deceased-donor human kidney in January 2026. The human kidney functioned immediately, and researchers said follow-up showed no evidence that the earlier pig transplant had sensitized his immune system in a way that interfered with the human organ.

Lead author Dr. Leonardo Riella said the shortage of human donor organs remains one of the biggest challenges in transplantation.

Researchers hope xenotransplantation could eventually provide patients with an alternative to years of dialysis while they wait for a suitable human kidney.

The procedure involved a genetically engineered pig kidney supplied by biotechnology company eGenesis and was performed under the US Food and Drug Administration’s Expanded Access Investigational New Drug program.

Researchers said the case also highlighted challenges that still need to be addressed, particularly the prevention of vascular injury and improving immunosuppressive strategies before pig-to-human kidney transplantation can be used more widely.