A genetically modified pig liver that was transplanted into a brain-dead patient appeared to function successfully inside their body for 10 days, according to the scientists who performed the groundbreaking procedure.
The surgery, at a Chinese hospital last year, is thought to mark the first time a pig liver has been transplanted into a human. It raises the prospect of pig livers serving as a “bridging organ” for patients on the waiting list for a transplant or to support liver function while their own organ regenerates.
Prof Lin Wang, who led the trial at Xijing hospital in Xi’an said: “This is the first time we tried to unravel whether the pig liver could work well in the human body and … whether it could replace the original human liver in the future. It is our dream to make this achievement.”
The advance is the latest in a series of transplants involving pig organs since 2022. Surgeons in the US and China have transplanted pig hearts, kidneys and a thymus gland into a small number of patients. Several died within months, although their severe illness at the outset meant it was unclear whether the transplants were a factor. But others have made a good recovery and have left hospital.
The latest procedure was carried out in a 50-year-old man diagnosed with brain death after a severe head injury. The patient’s own liver was intact and, in a surgery that took more than 10 hours, the organ taken from a genetically modified Bama miniature pig was plumbed into his blood supply as an additional liver.
The pig had six genetic modifications aimed at preventing immune rejection. These included deactivating genes that contribute to the production of sugars on the surface of pig cells, which the human immune system attacks, and introducing genes that express human proteins to “humanise” the liver.
After the transplant, the pig liver showed signs of functioning, including producing bile, which helps break down fats in the digestive system, and porcine albumin, a blood protein.
“There was good evidence of compatibility, which is really exciting,” said Peter Friend, a professor of transplantation at the University of Oxford. “Normally if you put a pig organ in it will be stone dead in a few minutes because you get hyper-acute rejection.”
The team behind the advance, described in the journal Nature, said it was not clear whether the liver would have been able to fully support the patient, given that he had an existing liver and because the liver was removed after 10 days at the request of his family. “We could not see whether the pig liver could support a patient with severe liver failure,” said Wang.
Even if pig livers only partly replace liver function, they could still be valuable as a “bridging” transplant. Friend said that “elegant surgical plumbing” used by the team meant this could be a relatively straightforward procedure.
“They basically slot the liver into … the main artery that runs from the leg towards the heart,” he said. “That makes it safer and much less prone to complications and something that can be removed as and when it’s not needed.”
Prof Muhammad Mohiuddin, director of the cardiac xenotransplantation programme at the University of Maryland, said: “This is a major leap forward for the field. With a liver, you don’t have to keep it for the rest of your life.
“You can use it as a bridge until a human liver is available for transplant or it can be used as a partial support until the liver regenerates. I firmly believe that this can work.”
