Kidney failure patient survived 271 days without dialysis on a pig kidney before needing a human transplant; pig organ didn't infect him throughout the xenotransplantation

A patient who lived for 271 days without dialysis on a genetically edited pig kidney has become the first person to successfully transition from a pig organ to a human kidney transplant, doctors at Massachusetts General Hospital have reported.

The case, detailed in a study published in The Lancet on September 3, is being described as the longest recorded survival on a pig kidney in a living human, and the clearest evidence yet that pig organs could serve as a temporary "bridge" for patients waiting on the human organ donor list.

Who the patient is


The patient, Tim Andrews, was 66 years old when he received the genetically modified pig kidney in January 2025 under an FDA Expanded Access programme. The organ began functioning immediately after transplant.

Doctors treated one early episode of rejection successfully. Throughout the entire period the pig kidney was in place, no infection passed from the pig organ to Andrews, addressing one of the central safety worries around animal-to-human organ transplants.

How the pig kidney eventually failed

Around six months after the transplant, doctors reduced Andrews' immunosuppression medication because of an infection. Following this, the pig kidney developed microvascular injury and inflammation, which progressively led to organ failure.

Andrews then received a donated human kidney, which functioned immediately with no signs of complications during follow-up.

How this compares to the first case

The world's first living recipient of a genetically engineered pig kidney received the transplant in 2024, also at Massachusetts General. That patient survived 52 days before dying of cardiac causes unrelated to the transplant. No prior case had documented xenograft survival beyond two months, or shown a successful transition from a pig kidney to a human one.

Doctors say Andrews' case is the first to demonstrate both a long-term "bridge" and a clear pathway to eventual human transplantation.

Why doctors are calling this a breakthrough

"The organ shortage is the greatest crisis we have right now in transplantation," said Leonardo Riella, lead author of the study and a Harvard Medical School associate professor of surgery at Mass General. He said the vision is for pig kidneys to eventually help patients get off dialysis while they wait for a human donor organ, and potentially serve as a long-term treatment option in their own right once safety and durability are established.

eGenesis, the biotechnology company that supplied the genetically edited pig kidney, reported the same day that a second, unrelated patient had also transitioned from a pig kidney to a human kidney transplant.

What researchers say needs work

Doctors noted that the microvascular injury seen in Andrews' pig kidney has implications for how future xenotransplant patients are treated, including how immunosuppression is managed, how donor pigs are genetically engineered, and how patients are monitored during the transplant.