Pig kidney kept man off dialysis for 9 months, serves as ‘bridge’ to human organ

A genetically modified pig’s kidney kept a 66-year-old man with end-stage kidney failure free of dialysis for a record nine months before he successfully received a human kidney, according to a study published in The Lancet.The report, titled “Porcine kidney xenotransplantation as a bridge to allotransplantation: a first-in-human study,” detailed the procedure performed at Massachusetts General Hospital in Boston. (Unsplash)This is the first time a porcine organ has served as a temporary “bridge” to human allotransplantation, offering hope for addressing the severe global shortage of donor organs.The report, titled “Porcine kidney xenotransplantation as a bridge to allotransplantation: a first-in-human study,” detailed the procedure performed at Massachusetts General Hospital in Boston.Kidney transplantation provides the best survival and quality of life for patients with end-stage kidney disease, but the demand for the organ far exceeds supply.According to the authors, kidney xenotransplantation offers a potential solution to the organ shortage, but questions remain regarding durability, zoonotic infection risk, and whether the immunological response to the xenograft elicits sensitisation that could complicate subsequent allotransplantation.Transplanting genetically engineered pig organs has been proposed as a solution to the organ shortage. The first pig kidney transplant into a living person, in 2024, ended after 52 days when the patient died from unrelated heart problems. No previous studies have documented xenograft survival beyond two months.Last year’s study titled ‘Xenotransplantation of a Porcine Kidney for End-Stage Kidney Disease’ highlights the first case and how xenotransplantation offers a potential solution to the organ shortage crisis.The paper said that the xenograft functioned immediately. The patient’s creatinine levels decreased promptly and progressively, and dialysis was no longer needed. After a T-cell–mediated rejection episode on day 8, intensified immunosuppression reversed rejection.“Despite sustained kidney function, the patient died from unexpected, sudden cardiac causes on day 52; autopsy revealed severe coronary artery disease and ventricular scarring without evident xenograft rejection,” said the authors in the paper.In the past 5 years, genetically engineered porcine kidneys have been transplanted into deceased human recipients, showing technical feasibility and providing important translational insights into human xenotransplantation. Building on these preclinical and translational studies, a genetically engineered porcine kidney was subsequently transplanted into a living patient with no evidence of organ rejection.In this new case study, the patient had kidney failure caused by type 2 diabetes. He had an estimated 9% chance of receiving a human kidney within five years, against a more than 40% risk of dying or being removed from the waiting list.The kidney came from a Yucatan miniature pig and was genetically engineered to be compatible with the human immune system. The transplantation took place at the Massachusetts General Hospital, Boston, USA, with a gene-edited porcine kidney; eGenesis incorporating the deletion of major glycan xenoantigens (sugar molecules on animal cells that cause the human immune system to reject transplanted animal organs), inactivation of porcine endogenous retroviruses (viral genetic sequences integrated directly into the DNA of all pigs that pose a potential safety risk during animal-to-human organ transplants), and insertion of seven human transgenes (human genetic material). The recipient was also put on immunosuppressants to minimise chances of organ rejection.The kidney was transplanted in January 2025 and began working immediately. After roughly six months, damage developed in the kidney’s blood vessels which progressed to organ failure and the kidney was removed approximately nine months after transplantation. The patient did not produce any detectable antibodies against the pig kidney, suggesting a mechanism different from that typically seen in organ transplant rejection.After several months back on dialysis, the patient received a kidney from a deceased human donor, which worked well during the six months of follow-up. No new antibodies against human tissue were detected, indicating that the pig kidney had not made it harder for the human kidney transplant to function successfully. No pig viruses or other pig pathogens were detected at any point.The authors emphasised that this case showed that porcine kidney xenotransplantation can provide prolonged renal support and be discontinued without clinically significant allosensitisation or zoonotic infection. Early cellular rejection resolved with treatment, whereas later graft failure was associated with microvascular injury that progressed to thrombotic microangiopathy despite a negative donor-specific crossmatch, suggesting that mechanisms beyond conventional antibody-mediated rejection contributed to late graft injury.“Kidney xenotransplantation has the potential to provide prolonged dialysis-free support while also serving as a bridge to subsequent human allotransplantation,” they said in the paper.The authors, however, caution that this was a single patient with no comparison group, and that the outcome reflects careful patient selection and intensive specialist care that may not be available elsewhere. They said that while the findings support pig kidney transplantation as a potential bridge for people facing long waits for a human kidney, further research is needed.Kidney transplant surgeons in India, a country where demand for an organ for transplantation far exceeds the supply -- 200,000 patients need a kidney transplant at any point, but not more than 1,500 surgeries are performed annually -- said they need to see more results.“This was a pilot project of sorts right now; therefore, we need to wait and watch. I’d say we would need at least 5-year results, and that too in large numbers, before anything like this can be attempted here,” said Dr Anup Kumar, professor and head unit, department of Urology, Robotics, & Renal Transplant, Safdarjung Hospital.