A kidney from a gene-edited pig has functioned well for days after being transplanted into a brain-dead human patient. The surgery, the first of its kind in China, shed light on the possibility of transplantation from nonhuman sources for patients in need.

A team led by Qin Weijun, a senior doctor at Xijing Hospital in Xi'an, Shaanxi province, performed the surgery on March 25. In a procedure that lasted more than six hours, the team removed the patient's kidneys and connected the pig kidney to the patient's bladder and ureter.

Over a nine-day observation period, the transplanted kidney functioned properly and generated urine normally, the hospital said in a statement issued on Thursday.

"The study of xenotransplantation — organ transplantation from nonhuman sources — has entered an acceleration period, and it provides a creative solution for those suffering from a shortage of available organs," said Dou Kefeng, an academician from the Chinese Academy of Sciences who oversaw the surgery. "It may buy precious time and extend the lives of numerous patients."

The pig involved in the surgery weighed 42.5 kilograms and was provided by Clonorgan Biotechnology in Chengdu, Sichuan province. With gene-editing technologies, three genes that would lead to acute rejection reactions were removed, while two human genes that regulate blood functions were added.

The patient was pronounced brain-dead in three separate evaluations, and relatives agreed to allow the research so that it could contribute to human medical advancement. The procedure also underwent systematic academic and ethical evaluations.

Over the past several months, Xijing Hospital, which is affiliated to Air Force Military Medical University of the People's Liberation Army, has performed several xenotransplantation procedures, including transplanting a pig's liver into a brain-dead patient, as well as transplantation of multiple organs into monkeys.

In July, a team led by Dou successfully transplanted the skin of a gene-edited pig to a patient with severe burns. About 50 days after the surgery, the patient's own skin grew back, the pig skin grafts peeled off and the wounds completely healed. Subsequent genome sequencing showed no evidence of germs that infect pigs.

More than 300,000 people in China suffer from terminal organ diseases every year. But no more than 20,000 transplant surgeries are performed each year, and many have lost their lives waiting for suitable organs.