Chinese doctors announced on Wednesday that they had successfully transplanted a liver from a genetically modified pig into a brain-dead human for the first time, offering a glimmer of hope for a potential life-saving organ donation option in the future.
The procedure, carried out at the Fourth Military Medical University in Xi'an, China, marks a significant breakthrough in organ transplantation.
Pigs have been identified as promising animal organ donors in recent years, with several living patients in the United States having received pig kidneys or hearts.
However, transplanting livers has proven to be more challenging, and up until now, no pig livers had been tested inside a human body. Given the escalating global demand for liver donations, researchers see genetically modified pigs as a potential temporary solution for patients enduring long waiting times for human organ transplants.
The liver, sourced from a miniature pig with six edited genes designed to enhance its suitability for donation, was transplanted into a brain-dead adult at the Xi'an hospital on March 10, 2024.
The trial was discontinued after 10 days at the family's request, with doctors stating that all ethical guidelines had been strictly adhered to.
According to the study published in Nature, the patient, whose identity and gender were not disclosed, still retained their original liver, receiving what is known as an auxiliary transplant.
The hope behind this procedure is that the transplanted pig liver could serve as a "bridge organ," temporarily supporting the liver of patients waiting for a human donor.
Over the 10-day period, the medical team closely monitored the pig liver's blood flow, bile production, immune response, and other essential functions.
Lin Wang, a study co-author and doctor at the Xi'an hospital, said, "The pig liver functioned really well" and "smoothly secreted bile," adding that it also produced the key protein albumin.
"It's a great achievement" that could provide future assistance to those suffering from liver problems, he noted during a press conference.
While many researchers have praised the progress made, they have also emphasised that the results are not conclusive proof that a pig liver could permanently replace a human liver.
Lin pointed out that liver transplants present more challenges than heart transplants, as the liver performs multiple critical functions, such as filtering blood and breaking down substances like drugs and alcohol.
Despite producing bile and albumin, the pig liver generated far smaller amounts of these substances than a human liver would, according to Lin. He stated that further research, including studying the pig liver for longer than 10 days, would be necessary.
Looking ahead, the doctors plan to test the gene-edited pig liver in a living human. Lin acknowledged the importance of collaboration with US researchers in advancing this field. "To be frank, we have learned quite a lot from all the research performed and investigated by the United States doctors," he said.
Oxford University transplantation professor Peter Friend, who was not involved in the study, described the results as "valuable and impressive." However, he cautioned, "this is not a replacement for liver transplantation from human donors (at least in the near-term)."
Friend went on to explain that the experiment served as an important test of the compatibility of genetically modified pig livers with humans, suggesting that in the future, such livers could provide support to patients in liver failure.
While the study marks a major step forward, Lin acknowledged that more work lies ahead. "We still need more research," he concluded.
The transplant research follows a previous experiment in 2024 at the University of Pennsylvania, where a pig liver was attached to a brain-dead patient but not transplanted into the body.
Last year, two US recipients of pig heart transplants died. On a more positive note, Towana Looney, 53, is now recovering at home in Alabama after receiving a pig kidney transplant on November 25, 2024.
