Tejal Somvanshi
For years, the question in organ transplantation research has been whether a pig’s kidney could ever work inside a human body. A case published in The Lancet on September 3, 2026, reports a specific advance in that question.
Tim Andrews received a genetically edited pig kidney in January 2025. He then received a human donor kidney in January 2026. Between those two operations, he lived for 271 days without needing dialysis. That 271-day span is the longest recorded period of dialysis-free survival after a pig kidney transplant in a living human. It is also the first documented case of a patient successfully progressing from a pig kidney to a human kidney transplant.
The research came out of Harvard Medical School and Massachusetts General Hospital, part of Mass General Brigham. The transplant was performed under an FDA Expanded Access Investigational New Drug application rather than as routine clinical care.
The pig kidney was not just any animal organ. The donor pig, developed by the biotechnology company eGenesis, carried 69 separate genomic edits. These modifications fall into three categories.
First, the scientists inactivated porcine endogenous retroviruses — genetic sequences that exist in pig DNA and could theoretically transfer to a human recipient. Second, they deleted three pig-cell glycan antigens that can trigger strong immediate human immune responses and rejection. Third, they inserted seven human genes into the pig’s genome that help the organ behave more like a human body expects — regulating inflammation, clotting, and immune activation.
The kidney functioned immediately, and no pig pathogen transmission was detected during monitoring. An early episode where the immune system attacked the organ — a T-cell-mediated rejection — was reversed with targeted treatment.
The complication came when Andrews developed an unrelated infection. To manage it, doctors had to reduce his immunosuppression medication — the drugs that stop the immune system from attacking the pig kidney. Without full protection, the organ began to develop chronic microvascular injury. Blood vessels inside the kidney were gradually being damaged. The kidney’s function declined.
At that point, Andrews was listed on the national organ transplant waitlist. When a deceased-donor human kidney became available, he received it. After the human transplant, the kidney began functioning immediately and there was no sensitisation — meaning his immune system did not carry over a triggered response from the pig organ that would attack the new human one.
The key concept here is “bridge transplantation.” The pig kidney was not intended to last forever. The clinical question being explored is whether an animal organ can keep a patient off dialysis and stable long enough for a suitable human kidney to become available. In this case, the pig kidney kept the patient off dialysis for 271 days before the human transplant.
Researchers at Mass General Brigham have specifically described the organ shortage as a major crisis. In India, for context, kidney transplant numbers have risen from 4,990 in 2013 to 18,378 in 2023 — but the organ donation rate remains critically low. In 2023, 11,791 kidney transplants in India used living donors while only 1,635 came from deceased donors.
This case does not mean pig kidneys are ready as a standard treatment. Longer-term safety data, durability evidence, and broader clinical studies are still needed. It establishes a reported 271-day dialysis-free period followed by successful transplantation of a deceased-donor human kidney, providing evidence for xenotransplantation as a potential bridge.
The reported case therefore provides evidence relevant to the question of whether a pig kidney can serve as a temporary bridge to a human transplant.
