Genetically modified pig kidney functions in US man for 271 days

A kidney transplanted from a genetically modified pig functioned inside a US man for a record 271 days, doctors at Mass General Brigham hospital in Boston revealed.

The breakthrough offers hope for the more than 100,000 Americans and 7,000 Britons waiting for kidney transplants, with only a fraction receiving donor organs each year. Tim Andrews, 66, who suffered end-stage kidney disease due to type 2 diabetes, received the pig kidney in January 2025. The organ worked immediately, sparing him months of dialysis, which he described as a "light at the end of the tunnel." Without the transplant, he faced a potential seven-year wait for a human kidney—while average survival on dialysis is just five years.

The pig kidney, sourced from a Yucatan miniature pig with 69 genetic modifications to make its organs more compatible with humans, eventually failed and was removed in October 2025. Andrews briefly returned to dialysis before receiving a human kidney transplant in January this year, which continues to function well. Researchers modified the pig’s DNA to remove features that trigger human immune attacks, add protective human genes, and disable hidden viruses in pig DNA to prevent infection.

Doctors call the organ shortage a "crisis" and see xenotransplantation—using animal organs—as a critical bridge until human donors are available. While challenges remain, this case proves pig kidneys can sustain patients for extended periods, offering a lifeline for those running out of time.