A Genetically Modified Pig Kidney Kept a Man Alive for a Record Nine Months, Allowing Him to Wait for a Donated Human Organ

For the first time, a genetically modified pig kidney has served as a temporary bridge to a human organ transplant, keeping a man alive and off dialysis for nine months while he waited for a human kidney to become available. Researchers describe the case in a paper published September 3 in the Lancet. The man in question is Tim Andrews, a now 68-year-old New Hampshire resident who had been suffering from end-stage kidney disease.

He was on dialysis, a process that removes excess fluid and waste from the blood when the kidneys stop working properly, and his prognosis wasn’t good. But Andrews had heard that genetically modified pig kidneys were being tested in humans, so he decided to volunteer for the experimental—and risky—procedure. I realized, ‘OK, I’m a dead man.

I’m a dead man walking.’ So, I said to myself, ‘What have I done? What have I done with my life? This is an opportunity for me to do something that most people don’t get an opportunity to do, and that’s to help humanity.’” In January 2025, surgeons at Massachusetts General Hospital in Boston transplanted a kidney from a Yucatan miniature pig into Andrews.

The pig, which Andrews nicknamed Wilma, had received 69 genetic edits designed to reduce the risk of porcine virus transmission and lower the chances of Andrews’ immune system rejecting the organ, reports the Guardian’s Andrew Gregory. After recovering from the procedure, Andrews felt better than he had in years. So, for me, it was beautiful.” About six months after the transplant, Andrews developed a bacterial infection from methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to many antibiotics.

His doctors reduced his immunosuppression drugs, which were helping prevent his body from rejecting the foreign organ. But then the pig kidney’s blood vessels started to become damaged. Eventually, the damage escalated to organ failure.

Andrews lived with the pig kidney—and was able to avoid dialysis—for a record 271 days. Though the kidney ultimately had to be removed, doctors consider the transplant overall to be a success. After surgeons removed the pig kidney, Andrews went back on dialysis for three months.