Genetically Modified Pig Kidney Sustains US Patient for Record 271 Days

Doctors in the United States have achieved a major medical milestone. A pig kidney has successfully worked inside a human patient for 271 days, which is the longest time on record.

The patient, Tim Andrews, was 66 years old when he had the transplant in January 2025. He suffered from kidney failure because of type 2 diabetes. He faced a difficult situation because the waiting list for a human kidney in the US is very long. About 100,000 people are waiting for a transplant, but doctors can only perform 25,000 of these operations each year. In the UK, more than 7,000 people are on the list. Andrews learned that he might wait seven years for a kidney, but patients on dialysis live for only five years on average.

To solve this crisis, surgeons at Mass General Brigham hospital are testing xenotransplantation, which means using organs from other species. For this surgery, scientists used a Yucatan miniature pig. They modified the pig's DNA 69 times to humanise the organ. These changes help to hide the kidney from the human immune system, which would normally destroy a pig organ immediately.

The transplanted kidney worked immediately and kept Andrews off the dialysis machine for nine months. He said the transplant gave him hope and the chance to live his life freely. Although the pig kidney eventually failed in October 2025 and doctors had to remove it, it served as a successful bridge. Andrews went back on dialysis for 82 days until he received a human donor kidney in January of the following year.

Dr. Leonardo Riella explained that xenotransplantation could be an excellent alternative for patients who do not have a living donor. If scientists can make these organs last longer, they will save many lives.