Transplanting a pig’s liver into a living person makes it more of a norm

Transplanting organs from non-human animals into humans could revolutionize medicine, potentially saving human lives Thousands of lives are lost while people wait for organs. Scientists have previously experimented with giving humans pig hearts and kidneys, and have now reported transplanting an animal’s liver into a living person for the first time.

“This is really, really groundbreaking,” he says. Heiner Wedemeyer at the Hannover Medical School in Germany, who was not involved in this procedure. “The patient was on the verge of death, but because of the transplant, he survived for half a year.”

The complexity of the liver meant that only such surgeries existed It has been tested on brain dead peopleWith signs of success. “The heart is just a muscle that pumps blood,” Wedemeyer says. “The kidneys are also easy, because they just need to remove things from the body. But the liver is different because it produces many different proteins involved in many metabolic processes.”

Likewise, heart and kidney transplants in living people showed signs of early success, but complications later developed. With heart transplantation, this has been linked to the possibility of transmitting the pig virus.

now, Beicheng Sun Researchers at Anhui Medical University in China and colleagues reported transplanting a pig liver into a 71-year-old man. The recipient’s liver function has been deemed too poor for a conventional transplant to have a good chance of success, due to a large tumor and heavy scarring from hepatitis B infection. Thousands of people die every year waiting for a liver transplant, so every procedure must be carefully justified, says Sun.

However, the man still needed some form of transplant, as his tumor could have fatally ruptured at any moment, Sun says. With the recipient’s consent, in May 2024, Sun and his team replaced the right portion of his liver, which contained the tumor, with part from an 11-month-old piglet. The operation, which took five hours, involved connecting blood vessels from the pig’s liver to those on the left side of his organ.

To prevent the liver from being rejected by its immune system, three genes were disabled in the pig and seven genes were introduced, so the organ functions more like a human organ. The man also took immunosuppressive medications, and the team carefully checked that his liver was not infected with any pig viruses.

Almost immediately, the liver began secreting bile, a fluid produced by the liver to help break down fats from food. Within weeks, the recipient’s bile and albumin levels — a protein made by the liver that prevents too much fluid from leaking from blood vessels — rose to healthy amounts, Sun says.

But about a month after the operation, he developed life-threatening blood clots, forcing the team to remove the transplanted organ. This may be due in part to over-activation of part of the recipient’s immune system and production of abnormal levels of certain blood clotting proteins, which a healthy liver also makes. This is more likely to happen with pig transplants, Sun says, because of how different the animal is from humans.

The man lived for another five months, with only the left side of his liver, and then died of a stomach bleed Common with liver scarring,” says the Sun. Both Sun and Widmaier say the bleeding probably has nothing to do with the transplant.

Although the man died, the procedure can still be considered a partial success, because otherwise he likely would have died shortly after the tumor was removed, Wedemeyer says. What’s more, the recipient’s liver was partially regenerated while the transplant was doing well, which may be why he survived for months after it was removed, he says.

This procedure has advanced our understanding of human organ transplantation, raising the possibility that pig livers could buy time for those waiting for human organ transplants, Wedemeyer says. They could also enable remaining liver tissue to regenerate enough so that people no longer need the procedure, Sun says.

But it will likely take at least a decade before pig livers can be used to permanently replace human livers, Sun says. First we need to significantly reduce the risk of complications, for example by making more genetic modifications, says Sun.

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