China doctors transplant gene-edited pig liver into a man — He lived 171 days; Scientist says 'this is a very key finding'

Doctors in China have transplanted a genetically modified pig liver into a 71-year-old man, who lived for 171 days after the procedure, including 38 days with the pig organ in place – a first to be published in a peer-reviewed journal, CNN reported.

Scientists have previously achieved early success transplanting genetically modified pig kidneys and hearts into humans, and pig livers have been transplanted into brain-dead individuals. However, experts in xenotransplantation – the use of animal organs in people – have expressed concerns about the suitability of the liver for such procedures.

“Everyone always says, ‘oh, liver is too complicated to transplant, compared to the heart or kidney,’ but after this, in the future, I think people will think differently. I think liver is good if we can get enough human genes in the pig,” said Dr Beicheng Sun , president of the First Affiliated Hospital of Anhui Medical University and a co-author of the new study.

Unlike hearts and kidneys, which have more narrow functions, the liver is more complex to replace with a pig organ because it is large and has a dual blood supply and multiple functions. The liver filters blood, removes toxins and waste, processes nutrients, detoxifies harmful substances such as alcohol and drugs, produces bile to aid digestion, manufactures proteins that help blood clot, and plays a crucial role in regulating blood sugar. Last year, doctors at Penn Medicine conducted the world’s first successful external liver perfusion using a gene-edited pig organ.

Blood from a brain-dead patient circulated through a pig liver outside the person’s body. In that case, the pig liver showed no signs of inflammation during the 72 hours it was tested, and the patient’s body remained stable. A transplanted pig liver given to a brain-dead patient in China in March-2024 was removed at the family’s request ten days after surgery. There had been no signs of immune rejection or accumulation of inflammation.

Experts say the new study, published Thursday in the Journal of Hepatology, suggests that pig-to-human liver transplantation shows promise as a bridge to help a person with a serious liver condition survive long enough for their own liver to recover or for a donor human liver to become available.

“In the future, maybe the left side can get a real chance to regenerate, and in that case, we would remove the graft, and that would be enough to support the life, or at least we know we can wait one or two months for a graft from a human that could save his life. I think this is a very key finding,” said Dr. Beicheng Sun , president of the First Affiliated Hospital of Anhui Medical University and a co-author of the new study.

With more than 1 lakh people on organ transplant waiting lists in the US alone and over 9,000 waiting for a liver transplant, the demand for human organs far outpaces the supply. Livers are the second largest need after kidneys, according to the US Health Resources & Services Administration.

Scientists have been exploring alternatives for decades, including the use of pig organs due to their similarity to human organs. In the case described in the new paper, doctors at the First Affiliated Hospital of Anhui Medical University in China transplanted a liver from an 11-month-old pig into a 71-year-old man in May-2024. The pig, a clone, had ten gene edits to reduce the possibility of infection or rejection of the organ. Doctors also administered drugs to suppress the man’s immune system to prevent rejection of the foreign organ.

The man had initially been hospitalised for hepatitis B-related cirrhosis, a condition in which scar tissue replaces healthy tissue, impairing liver function and sometimes leading to liver failure. He also had a large tumour in the right lobe of his liver, but efforts to shrink the tumour with high-concentration chemotherapy targeted at its blood supply were unsuccessful. In some cases, surgeons can remove part of the liver, but the researchers behind the new study said that what remained of the man’s liver would probably have been too small to meet his metabolic needs.

After almost three weeks in the hospital, the man developed severe abdominal pain, and tests indicated that the tumour was at risk of rupturing. Doctors tested family members for potential liver tissue donation, but no suitable match was found, so a gene-edited pig liver was considered the only remaining option to save his life. He and his daughter discussed the experiment with the doctors and agreed to proceed.

“We need to have great respect for this patient and their family,” Sun said. “The patient provides such a special contribution to the field of this science, and we need to be grateful for all of these patients who have made such a big contribution to this field.”

Doctors removed the tumour and transplanted the genetically modified pig liver onto the remaining portion of the man’s liver. The transplant appeared successful initially. The pig liver turned red immediately, and bile – which helps remove waste products and aids in the absorption of fats – began to drain from the external bile duct, with secretion progressively increasing over time.

Within the first day, there was a significant increase in other liver function indicators, and there were no initial signs of inflammation or rejection. There were no signs of acute rejection in the man’s body on day ten after the surgery, according to the researchers. Instead, what remained of his liver seemed to perform better than before the surgery. An ultrasound showed that the portal vein, hepatic artery, and hepatic vein blood flow in the transplanted pig liver were functioning normally.

However, by day 25, the patient’s heart began to show progressive signs of stress. Tests on days 28 and 33 revealed inflammatory changes related to the transplant, and doctors adjusted the immune-suppressing drugs. Other signs indicated that the transplant was not performing as well as initially, suggesting the man had developed xenotransplantation-associated thrombotic microangiopathy, a condition where microscopic blood clots damage small blood vessels and organs.

On day 37, the man’s blood pressure plummeted, and his heart rate increased, causing him to lapse in and out of consciousness. At that point, his own liver was deemed capable of functioning sufficiently to sustain his body, so doctors removed the pig organ on day 38. The man’s liver continued to function well afterward.

On day 135, the man developed upper gastrointestinal bleeding and died from this bleeding 171 days after the transplant procedure. The study authors stated that the research provided critical insights into the challenges and feasibility of such transplants.

It demonstrated that pig-to-human liver transplantation “can provide effective hepatic support while preserving part of the native liver, confirming its clinical feasibility as a bridging strategy.” Dr Heiner Wedemeyer , a professor and chairman of the Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology at Hannover Medical School in Germany, co-authored an editorial published alongside the study on Thursday.

He wrote that the experiment showed “a cause for cautious optimism” as well as a “reminder of how far the field must still travel.” “It’s really groundbreaking,” Wedemeyer told CNN. “For me as a transplant hepatologist, it really opens completely new views and ideas.” Wedemeyer said he saw a patient Wednesday morning who had acute liver failure and did not qualify for transplantation with a human organ because of some cancer issues.

“If I would have had, at this stage, use of a pig liver to bridge her – because she may need three, four, five, six, seven weeks to recover with her own liver – I would have done this,” he said. “A pig liver gives us completely new opportunities, and that can really be promising for our patients.”