Gene-Edited Pig Kidney Keeps Patient Off Dialysis for 271 Days in Medical First
A genetically edited pig kidney kept a 66-year-old patient with end-stage kidney disease free from dialysis for 271 days before it was replaced with a deceased-donor human kidney. The case is the longest reported dialysis-free survival after a pig kidney transplant and the first documented transition from a pig kidney to a human donor kidney.
The pig kidney later developed inflammation and blood-vessel damage, but researchers found no evidence that it affected the patient’s eligibility for a human transplant. The result advances xenotransplantation research while highlighting the need for further study of organ durability, immune reactions, infection risks, and other complications.
A genetically edited pig kidney has helped a patient with end-stage kidney disease remain free from dialysis for 271 days before he successfully received a human kidney. The case, reported by researchers at Massachusetts General Hospital and Harvard Medical School, represents the longest dialysis-free survival reported after a pig kidney transplant in a living human and the first documented transition from a pig kidney to a human donor kidney.
The patient, Tim Andrews, was 66 when he received the genetically edited pig kidney in January 2025. At the time, doctors hoped the experimental transplant could provide a temporary solution while he waited for a suitable human donor. The kidney began functioning immediately, allowing Andrews to live without dialysis for more than nine months.
The procedure is part of a rapidly developing field known as xenotransplantation, which involves transplanting organs from animals into humans. Scientists are exploring genetically modified pigs because their organs can potentially be engineered to reduce immune rejection and other biological complications. The long-term goal is to develop a reliable source of organs for patients who cannot receive a human transplant quickly enough.
Andrews’ pig kidney eventually developed inflammation and microscopic blood-vessel damage, causing its function to decline. Doctors removed the organ, and after a period of dialysis, Andrews received a deceased-donor human kidney. The human kidney began functioning immediately, and researchers found no evidence that the earlier pig transplant had caused sensitization that would interfere with the new transplant.
The achievement could be particularly important because the shortage of donor organs remains one of the biggest challenges in transplantation. Researchers say xenotransplantation could eventually serve as a bridge, giving patients more time while they wait for a human donor instead of remaining dependent on dialysis.
However, scientists caution that the breakthrough does not mean pig kidneys are ready to replace human donor kidneys. More research is needed to understand how long genetically modified organs can function safely, how immune reactions can be controlled and how the risks of infection and other complications can be managed. The current evidence comes from a very small number of patients.
The new case nevertheless marks an important step in transplant science. If researchers can make genetically edited pig kidneys function safely for longer periods, xenotransplantation could eventually change how doctors approach the global shortage of donor organs and provide another pathway for patients waiting for life-saving kidney transplants.
