Part of a Pig Liver was Transplanted into a Human

Porcine liver surgery brings us closer to transplantation from other animal species

TO Umberto Basilio edited by Lewis asked

Chinese scientists have carried out what is believed to be the first transplant of a genetically modified pig liver segment into a human cancer patient. Surgeons reported that transplanted organ from a pig maintained the patient's metabolic functions properly for 38 days, after which it had to be removed due to complications. The patient lived another 133 days and died from gastrointestinal bleeding. The results were published on October 8 in the journal Journal of Hepatology.

Transplantation of organs from other animals to humans – known as xenotransplantation— has achieved notable success in recent years. The pig liver transplant “demonstrates that xenogeneic organs can not only survive for a short time, but also perform physiological functions in the complex environment of a living organism,” says Beicheng Sun, president of the First Affiliated Hospital of Anhui Medical University in China, who conducted the study with his colleagues. This “creates a bridge to give the patient more time” to recover or receive a donor organ if their liver has to be completely replaced.

The patient was at risk of liver rupture due to swelling on the right side of the organ. According to the doctors who treated him, the remaining left lobe was not enough to support life. Sun and his team implanted a piece of pig liver as a “support” graft. This left part of the man's own liver in place, allowing it to regenerate while the pig's organ temporarily supported his metabolism. The liver is the only human organ that can recover from injury.

About supporting science journalism

If you enjoyed this article, please consider supporting our award-winning journalism. subscription. By purchasing a subscription, you help ensure a future of influential stories about the discoveries and ideas shaping our world today.

The genetically engineered pig's liver began functioning immediately after surgery, secreting golden-yellow bile and synthesizing porcine albumin protein, blood clotting factors and bile acids. “This provided critical support to the patient by stabilizing his vital signs,” Sun says.

Complications appeared in the second month, when the patient developed thrombotic microangiopathy, a dangerous blood clotting disorder associated with immune activation. Doctors treated him with immunosuppressants and a blood filtering procedure called plasma exchange. When tests showed the condition was worsening, the team removed the pig's liver on day 38.

The man's remaining liver then took over and his condition remained stable for more than three months. One day, at the age of 171, he died of gastrointestinal bleeding unrelated to the transplant itself, the study authors reported.

The basic principle of assisted transplantation is not to remove the entire patient's own liver, Sun said. With temporary support from pig liver, the patient's left lobe was able to recover and regenerate. “This allowed the patient to survive on his own regenerated liver after removal of the pig liver,” he says.

The operation “is a step in the right direction,” says Muhammad Mohiuddin, a surgeon at the University of Maryland and president of the International Xenotransplantation Association, who was not involved in the experiment.

In August, a team of researchers from China performed the first-ever study. lung from pig to man xenotransplantation. And earlier this year, the US Food and Drug Administration approved first clinical trial of pig kidney transplantation.

Patients in the US are currently awaiting Food and Drug Administration approval for ex vivo pig liver perfusion, a procedure that allows doctors to use pig organs outside the body to temporarily replace the function of a damaged human liver, giving patients more time to wait for a suitable donor. Mohiuddin says new research shows that a similar result can be achieved with surgery. “Pig liver was not a replacement, but a bridge to support the human liver,” he says.

Although the procedure was “technically successful,” more research is needed to confirm that pig liver extract is indeed beneficial for human liver regeneration, says surgeon Parsia Vaghefi of UT Southwestern Medical Center, who was not involved in the new study. After such operations, “there's always the question of how functional a pig's liver actually is and how functional a human liver is,” he says.

When surgeons move to studies in which the native liver completely fails and the pig liver saves the patient, Vagefi says, “we'll be able to really see whether the pig liver provides enough support to actually connect someone” to a human liver transplant.

It's time to stand up for science

If you liked this article, I would like to ask for your support. Scientific American has been a champion of science and industry for 180 years, and now may be the most critical moment in that two-century history.

I was Scientific American I have been a subscriber since I was 12, and it has helped shape my view of the world. Let me know always educates and delights me, instills a sense of awe in front of our vast and beautiful universe. I hope it does the same for you.

If you subscribe to Scientific Americanyou help ensure our coverage focuses on meaningful research and discovery; that we have the resources to report on decisions that threaten laboratories across the US; and that we support both aspiring and working scientists at a time when the value of science itself too often goes unrecognized.

In return you receive important news, fascinating podcastsbrilliant infographics, newsletters you can't missvideos worth watching challenging gamesand the world's best scientific articles and reporting. You can even give someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you will support us in this mission.