A woman has survived with a transplanted pig kidney for more than nine months without requiring dialysis, according to a report published Thursday in Wired, marking the longest time anyone has lived with such an organ. The patient underwent surgery at Massachusetts General Hospital on November 22 last year, and the kidney has now functioned for 285 days. The achievement surpasses the previous record of 271 days set by Tim Andrews and represents a milestone in efforts to address the severe shortage of human donor organs.
The woman is the fifth patient to receive a kidney from eGenesis, a Cambridge, Massachusetts biotech company that uses Crispr gene editing to make pig organs suitable for human transplantation. More than 95,000 people in the United States are waiting to receive a kidney, yet fewer than 28,000 kidney transplants were performed in the country in 2025. Most patients needing a kidney transplant wait three to five years on average to receive one, though the timeline can stretch longer depending on blood type and other factors. While waiting, patients often require dialysis—four-hour sessions three times weekly in which a machine removes excess fluid and waste from the bloodstream—a procedure that damages blood vessels over time and takes a toll on the body.
The surgical team published findings Thursday in The Lancet medical journal detailing Andrews' case, determining that his pig kidney ultimately failed due to thrombotic microangiopathy, meaning tiny blood clots formed inside the transplanted organ. Andrews received his pig kidney in January 2025, had it removed in October after a period of declining function, returned to dialysis, then received a human kidney transplant this January. A second patient has also successfully received a human transplant after living with a pig kidney for eight months, according to eGenesis. Mike Curtis, CEO of eGenesis, says patients' health deteriorates the longer they remain on dialysis, "and their odds of getting a human transplant aren't rising fast enough to meet their declining health." Curtis notes that Andrews experienced "a radical improvement in his overall health while he was on the pig kidney versus if he had stayed on chronic dialysis."
The company used Crispr to remove certain pig genes that could trigger an immune response and added several human genes, making the organs less likely to be rejected immediately and reducing the risk of transmitting pig viruses to transplant recipients. Pig organs are similar in size and function to human organs, which is why scientists are investigating them as a potential bridge until human donor organs become available. People who receive human organ transplants must take immunosuppressive drugs to prevent their body from rejecting the transplanted organ, and organ rejection can occur at any time following surgery—from minutes afterward to many years later. The team is now using information from Andrews' case to adjust the immunosuppressant medications that pig kidney recipients receive and the frequency at which they take those drugs.
The Food and Drug Administration has approved eGenesis to conduct a formal trial in up to 33 patients with kidney failure who are between 50 and 70 years old and on the wait list for a human kidney, though that trial won't begin until 2027. In the meantime, eGenesis plans to perform additional transplants under the expanded access pathway, a special regulatory route that allows patients with serious or life-threatening conditions to access experimental treatments when no good alternatives exist. The company's next goal is to achieve a transplanted pig kidney that functions for a full year. The cases of Andrews and the second patient demonstrate that pig kidneys may serve as a viable temporary solution, potentially keeping patients healthier than dialysis while they await a permanent human organ. If the technology scales, hospitals could eventually offer these genetically modified organs as standard bridge therapy, fundamentally reshaping how transplant centers manage wait lists and patient outcomes.