A woman has lived with a genetically edited pig kidney for more than nine months without dialysis, setting a new record for kidney xenotransplantation—the transplantation of an animal organ into a human.
The woman received the pig kidney at Massachusetts General Hospital on November 22 of last year. As of Thursday, the kidney had been functioning for 285 days, according to Cambridge, Massachusetts-based biotechnology company eGenesis. The company used CRISPR gene-editing technology to modify the pig organ for human transplantation. The previous record for survival after a pig kidney transplant was 271 days, set by Tim Andrews.
Most people who need a kidney transplant wait three to five years for a donor organ, although the wait can be longer based on blood type and other factors. During that time, many patients require dialysis, a treatment that uses a machine to remove waste and excess fluid from the bloodstream. Dialysis typically involves three four-hour sessions each week and can place significant strain on the body, including long-term damage to blood vessels.
Genetically modified pig kidneys could provide a temporary alternative while patients wait for a human donor organ. Pig organs are similar in size and function to human organs, making them a potential solution to the global shortage of donor kidneys. Scientists are editing pig genes to reduce the risk of immediate organ rejection and limit the potential transmission of swine viruses to transplant recipients.
Patients’ health often declines the longer they remain on dialysis. “The likelihood of a human being receiving a transplant is not increasing as quickly as commensurate with their worsening health,” said Mike Curtis, CEO of eGenesis. The company used CRISPR to remove pig genes that could trigger an immune response and added a small number of human genes to improve compatibility with the human body.
“What we observed with Mr. Andrews was a fundamental improvement in his overall health compared to if he had been on chronic dialysis and compared to using pig kidneys,” Curtis said.
The woman is the fifth person to receive an eGenesis pig kidney through expanded access, a special regulatory pathway for patients with serious or life-threatening conditions who have no suitable treatment alternatives. The pathway allows the U.S. Food and Drug Administration to authorize experimental treatments in limited circumstances.
Andrews’ case suggests that a pig kidney may serve as a bridge to a human kidney transplant. He received a genetically modified pig kidney in January 2025, but doctors removed it in October after a temporary decline in kidney function. He returned to dialysis before receiving a human kidney transplant the following January. According to eGenesis, another patient’s pig kidney also functioned successfully for eight months after transplantation.
Curtis said eGenesis is learning from every transplant. In a study published Thursday in the medical journal The Lancet, the surgical team that treated Andrews described his experience in detail. Researchers concluded that the pig kidney ultimately failed because of thrombotic microangiopathy, a condition involving the formation of small blood clots in the transplanted organ.
Researchers are using those findings to adjust the doses and schedules of immunosuppressive medications given to pig kidney recipients. People who receive human organ transplants also need lifelong immunosuppressants to reduce the risk of rejection. Organ rejection can occur at any time after transplantation, from minutes after surgery to years later.
In the United States, 95,000 people are waiting for a kidney transplant. However, fewer than 28,000 kidney transplants are expected to be performed in the country in 2025 because of the shortage of donor organs.
The FDA has authorized eGenesis to conduct a formal clinical trial involving up to 33 patients ages 50 to 70 with kidney failure who are on the human kidney transplant waiting list. The trial is not expected to begin until 2027, but eGenesis plans to perform additional pig kidney transplants through the expanded-access pathway. The company’s next goal is to keep transplanted pig kidneys functioning for at least one year.
Source: www.wired.com