Pig kidney kept a man off dialysis for nine months in world first

A genetically modified pig’s kidney kept a man with organ failure off dialysis for nine months while he waited for a suitable human donor’s kidney to become available. This suggests pig kidneys could act as a temporary measure amid lengthy organ waiting lists, but they may also work as a permanent replacement one day.

“I think it’s incredible in terms of the science behind it and what they’ve achieved,” says Michelle Willicombe at Imperial College London, who wasn’t involved in the work.

For people with severe kidney disease, where these organs are failing and dialysis is needed, a kidney transplant provides the best chance of survival and better quality of life. However, demand for donor organs exceeds supply.

One possible solution is xenotransplantation, the transfer of organs from other animals into humans. In January 2022, a pig heart was transplanted into a person for the first time, but the recipient died several months later, possibly due to the presence of a pig virus. A pig liver transplant also occurred last year.

A pig’s kidney was transplanted into a living person for the first time in 2024. The recipient, Richard Slayman, aged 62, died 52 days later from cardiac-related causes. In the latest development, Tim Andrews, a 66-year-old man with end-stage kidney failure, opted to receive a kidney from a pig to avoid dialysis while he waited for a suitable human organ.

Leonardo Riella at Mass General Brigham hospital in Boston and his colleagues transplanted the kidney, which came from a Yucatan miniature pig, into Andrews in January 2025. The organ had been genetically modified to improve compatibility with the human immune system, such as by removing some sugars that we produce antibodies against and adding seven human genes.

The transplant was initially a success, and Andrews – who also received immunosuppression drugs to stop his body rejecting the organ – came off dialysis and resumed normal life. However, after about six months, he was admitted to hospital with a methicillin-resistant Staphylococcus aureus (MRSA) infection, which most antibiotics can’t kill.  

Riella and his colleagues reduced the immunosuppression drugs Andrews was on, but then damage started to develop in the kidney’s blood vessels. This progressed to organ failure, and the kidney was removed a record 271 days after transplantation. “He had a kidney that lasted nine months, which is mind-blowing,” says Riella.

Andrews went back onto dialysis for about three months, before finally receiving a suitable human kidney in January 2026. This marks the first time a pig kidney has been used as a temporary bridge to a human transplant.

“Such transplants may allow patients to avoid going through dialysis, which is so important because it causes so much wear and tear to the body,” says Riella. “Hopefully, maybe 15 years from now, pig kidneys will compete with a human kidney transplant, but you’re not there yet.”

The procedure is experimental, and Riella couldn’t give an estimate of how much it might cost. But in the US, there are about 600,000 people on dialysis, which can cost about $100,000 a year per individual, he says.

Riella says the team has now done five such transplants and two more case reports will be published this year, including one of a person who has already beaten Andrews’s record of nine months with a functioning pig kidney.

“I think these will be carried out more widely in the future, but it’ll be a little while,” says Willicombe, largely due to their probable high cost. Scientists should also continue researching artificial kidneys, as well as ways to regenerate damaged organs and optimise donated ones, she says.