HEFEI -- In a big leap for medical science, Chinese surgeons have successfully performed the world's first transplant of a gene-edited pig liver into a living human patient, who survived for 171 days after the operation.

This milestone, reported in the Journal of Hepatology this month, marks a significant advance in the quest to address the critical shortage of human donor organs.

The groundbreaking procedure was led by a team from the First Affiliated Hospital of Anhui Medical University, with the gene-edited pig liver developed by researchers from Yunnan Agricultural University.

The donor pig underwent extensive pathogen screening and a sophisticated 10-gene modification process. Three genes responsible for rapid antibody-mediated rejection in pigs were knocked out, while seven human genes were inserted to improve immune acceptance and prevent blood clotting complications, according to the paper.

The operation was conducted on May 17, 2024, and the recipient was a patient with a large, unresectable liver tumor in the right lobe. The genetically modified pig liver was transplanted as an "auxiliary" organ, meaning it was added to support the patient's own native liver.

It came after another team of Chinese researchers transplanted in April that year a genetically modified pig liver into a brain-dead patient at Xijing Hospital of the Air Force Medical University in Xi'an.

The post-surgery results in the latest case were initially highly promising. For the first 31 days, the 71-year-old patient showed no signs of acute rejection, and the pig liver functioned effectively.

However, a challenge emerged on day 38 when the patient developed a serious condition involving blood clots in the small vessels of the transplanted organ. Then, the clinical team removed the auxiliary liver.

The patient later suffered from recurrent upper gastrointestinal bleeding and passed away on day 171.

While the patient's ultimate survival was limited, the case proves the remarkable feasibility of a pig liver supporting a human patient for a clinically meaningful duration.

This achievement establishes xenotransplantation as a potential "bridge" therapy for those awaiting a human liver transplant.

"This operation does not yet open the door to widespread clinical use of pig livers. But it does establish proof-of-concept that such grafts can function in humans," says a review article published in the journal.