Chinese surgeons transplant liver from pig to human in world-first

A 71-year-old man in China lived for almost six months after receiving a liver transplant from a genetically modified pig, scientists have announced. The man's own liver had irreversible scarring caused by a hepatitis B infection and liver cancer, so he was not eligible for a human liver transplant.

This is the first time that a liver from a genetically-modified pig has been transplanted in a human for "therapeutic purposes". Two cases have previously been reported in brain-dead patients as part of preparatory work. Pigs are the most promising donor animals due to their availability, size and similarities to human organs.

The liver was taken from a genetically modified Diannan miniature pig, with gene edits designed to reduce the chances of the organ being rejected by the man's immune system.

Writing in the Journal of Hepatology, researchers described how the graft "functioned effectively" for the first month.

However, the graft was removed on day 38 following complications linked to the transplant - a condition called xenotransplantation-associated thrombotic microangiopathy (xTMA).

Researchers reported that treatment resolved the xTMA, but despite this the patient died 171 days after the transplant.

Lead investigator Dr Beicheng Sun, from the First Affiliated Hospital of Anhui Medical University in China's Anhui Province, said: "This case proves that a genetically engineered pig liver can function in a human for an extended period.

"It is a pivotal step forward, demonstrating both the promise and the remaining hurdles, particularly regarding coagulation dysregulation and immune complications, that must be overcome."

Overcoming the rejection of pig organs by the human immune system has been a complex challenge for more than four decades.

But gene-editing technology and new techniques to suppress the immune system have shown promise in several recent experiments.

In an accompanying editorial, Dr Heiner Wedemeyer, co-editor of the Journal, said: "This report is a landmark in hepatology. It shows that a genetically modified porcine liver can engraft and deliver key hepatic functions in a human recipient.

"At the same time, it highlights the biological and ethical challenges that remain before such approaches can be translated into wider clinical use.

"Xenotransplantation may open completely new paths for patients with acute liver failure, acute-on-chronic liver failure, and hepatocellular carcinoma. A new era of transplant hepatology has started."