US: Pig Kidney Transplant Helps Man Avoid Dialysis For 271 days

A pig kidney transplanted into a US patient functioned for 271 days, setting a record for the longest period a genetically modified pig organ has worked inside a human.

The transplant gave Tim Andrews, who had end-stage kidney disease caused by type 2 diabetes, more than nine months without dialysis while he waited for a human donor kidney.

Doctors at Mass General Brigham, United States, said the case provides further evidence that pig organs could one day serve as a temporary “bridge” for patients waiting for a human transplant.

Andrews was 66 when he received the pig kidney on January 25, 2025. The organ began working immediately and continued to function until doctors removed it in October that year.

He then underwent dialysis for 82 days before receiving a human donor kidney in January 2026, which has continued to work well.

For Andrews, the transplant offered relief from the uncertainty surrounding his condition. He had been told he could wait as long as seven years for a human kidney, while the average life expectancy for people on dialysis is about five years.

“I had a little bit of a shortage of time… it becomes very depressing,” he said.

He described the possibility of receiving a pig kidney as “hope” and the “light at the end of the tunnel”.

“Hope is the biggest thing, the chance to be free from the [dialysis] machine and live your life.”

The procedure is part of growing research into xenotransplantation, which involves transplanting organs from animals into humans as a way of addressing the shortage of donor organs.

Pigs are considered suitable for the research because their organs are broadly similar in size to human organs and the animals can be bred under controlled conditions.

However, an ordinary pig kidney would trigger an immediate and severe immune response in a human recipient. Researchers therefore used Yucatan miniature pigs whose organs had undergone 69 genomic modifications.

The modifications were designed to remove features of pig cells that the human immune system recognises and attacks, introduce human DNA to make the tissue less visible to the immune system, and disable viruses embedded in the pig’s genetic material to reduce the risk of infection.

In Andrews’ case, doctors initially detected signs that his immune system was rejecting the transplanted kidney. They managed the reaction by adjusting his medication.

The organ later developed blood-vessel damage after about six months, leading to inflammation and a gradual loss of function. Doctors said they could not establish the precise cause because there was no evidence of antibodies attacking the pig kidney.

The need for alternative sources of kidneys remains significant. In the US, about 100,000 people are waiting for a kidney transplant, while roughly 25,000 kidney transplants are carried out each year. More than 7,000 people in the UK are also on the kidney transplant waiting list.

Dr Leonardo Riella of the Centre for Transplantation Sciences at Mass General Brigham said the gap between demand and the availability of organs had created an urgent situation.