Doctors in China have reported a landmark success in xenotransplantation, stating that a genetically modified pig liver was transplanted into a 71-year-old man who lived for 171 days after the procedure.
For 38 of those days, the pig organ was in place, providing critical support, a first for a pig-to-human liver transplant to be published in a peer-reviewed journal.
The procedure, performed in May 2024 at the First Affiliated Hospital of Anhui Medical University, utilized a liver from an 11-month-old cloned pig that had undergone 10 genetic edits to minimize the risk of infection or rejection. The man was also given immune-suppressing drugs to prevent his body from rejecting the foreign organ.
While scientists have seen success transplanting pig hearts and kidneys into humans, the liver has long been viewed as a more challenging candidate due to its large size, dual blood supply, and diverse functions, which include filtering blood, removing toxins, and producing clotting proteins.
Dr. Beicheng Sun, president of the First Affiliated Hospital of Anhui Medical University and a co-author of the new study, expressed optimism: “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.”
Experts say the study, published on Thursday in the Journal of Hepatology, confirms the feasibility of using a pig liver as a bridging strategy. This approach would help a patient with severe liver disease survive long enough for their own liver to regenerate or for a suitable human donor organ to become available.
The patient had been hospitalized for hepatitis B-related cirrhosis and a large, inoperable tumor. Surgeons determined that removing the tumor would leave too little of his own liver to support his metabolic needs.
With no matching human donor available, the patient and his daughter agreed to the experimental xenotransplantation, a decision Dr. Sun emphasized was a significant contribution to the field of science.
Doctors removed the man’s tumor and transplanted the gene-edited pig liver onto the remainder of his native organ.
The transplant initially appeared successful. The pig liver quickly began functioning, turning red and secreting bile, with other liver function indicators significantly improving within the first day. There were no signs of acute rejection at day 10, and the man’s own remaining liver tissue seemed to be performing better.
However, by day 25, the patient’s heart began showing signs of stress, and tests indicated inflammatory changes. Despite changes to his immune-suppressing drugs, signs of rejection worsened, suggesting the development of xenotransplantation-associated thrombotic microangiopathy (microscopic blood clots damaging small vessels).
On day 37, the man’s condition deteriorated, and doctors removed the pig organ on day 38, as the patient’s own liver was considered capable of sustaining him. He continued to function well until day 135, when he developed upper gastrointestinal bleeding, which caused his death 171 days after the initial transplant.
Dr. Heiner Wedemeyer, a professor at Hannover Medical School in Germany and co-author of an editorial accompanying the study, called the experiment “groundbreaking.” He noted the procedure offers a completely new opportunity to bridge patients with acute liver failure who may not qualify for human transplantation.
The research provides crucial insight, confirming 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,” the study authors concluded.
The demand for human organs far outpaces the supply, with livers being the second biggest need after kidneys.
