Doctors at the First Affiliated Hospital of Anhui Medical University in China successfully pig liver transplant into a 71-year-old man in May 2024, according to a study published Thursday in the Journal of Hepatology. The patient lived for 171 days after the procedure, including 38 days with the pig organ functioning inside his body.

The case marks the first reported instance of a pig liver sustaining a human patient for more than a month, demonstrating what researchers describe as a significant advancement in xenotransplantation — the practice of using animal organs in humans.

“This finding shows that the liver can indeed be a viable option if enough human genes are introduced into the pig,” said Dr. Beicheng Sun, president of the hospital and co-author of the study.

Complex organ, cautious progress

Pig liver transplant are among the most challenging in medicine. Unlike hearts or kidneys, the liver performs multiple vital functions — filtering blood, producing bile, regulating sugar, and synthesizing proteins for blood clotting. Its complex structure and dual blood supply make it difficult to replicate with an animal organ.

The patient suffered from hepatitis B-related cirrhosis and had a large liver tumor that failed to respond to targeted chemotherapy. When other options ran out, doctors proposed a gene-edited pig liver as the only remaining chance for survival.

After discussions with his family, the man agreed to the experimental surgery. The pig, an 11-month-old clone, had 10 genetic modifications to minimize immune rejection and infection risks.

Operation and results

During surgery, Chinese doctors removed the tumor and connected the pig liver to the remaining portion of the man’s native liver. The transplanted organ immediately began functioning — turning red as blood flowed through it and producing bile within hours.

Within the first day, key liver function indicators improved, and no signs of inflammation or immune rejection were detected. After 10 days, both the pig liver and the man’s remaining liver tissue appeared healthy.

However, by day 25, the patient began showing signs of cardiovascular stress. Later tests indicated inflammation and microscopic blood clots, conditions often linked to xenotransplantation-related complications. Chinese doctors adjusted the patient’s medications, but the transplant’s effectiveness declined.

By day 38, his blood pressure dropped sharply, and doctors determined his own liver had recovered enough to function independently. The pig organ was removed successfully, and his liver continued to perform normally afterward.

The patient later developed gastrointestinal bleeding and died 171 days after the transplant.

Implications for the future

Experts say the case offers critical insights for future xenotransplantation trials. The findings indicate that pig livers could temporarily support patients with severe liver disease while waiting for human donors or while their own organs recover.

“This could act as a bridge therapy,” Sun said. “In some cases, the native liver might regenerate, or the patient could survive until a human donor organ becomes available.”

Dr. Heiner Wedemeyer, professor of gastroenterology and hepatology at Hannover Medical School in Germany, called the research “a cause for cautious optimism.” He said it represented both progress and a reminder of the challenges still ahead.

“With more than 100,000 people waiting for transplants in the United States alone, and thousands of them in need of a liver, this study shows a potential way to extend lives,” Wedemeyer said.

Scientists have been exploring genetically modified pigs as possible organ donors because their organs are similar in size and function to those of humans. Recent experiments have shown success with pig hearts and kidneys, but livers have remained particularly difficult due to their complex roles in metabolism and detoxification.

Despite the patient’s eventual death, researchers view the case as an important proof of concept. The study concluded that pig-to-human liver transplantation “can provide effective hepatic support while preserving part of the native liver,” confirming its potential use as a temporary solution for critical patients.

Wedemeyer said he expects more research to follow. “A pig liver gives us completely new opportunities,” he said. “For some patients, it could mean the difference between life and death while waiting for a human donor.”