In a groundbreaking medical achievement, Chinese doctors have successfully transplanted a genetically modified pig liver into a brain-dead human for the first time. The procedure, carried out at the Fourth Military Medical University in Xi’an, China, marks a significant step in the field of organ transplantation and offers hope for addressing the global shortage of donor livers.
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The research, published in the journal Nature, highlights the potential of pig organs in human transplantation. While genetically modified pig kidneys and hearts have been transplanted into living patients in the U.S., this marks the first time a pig liver has been placed inside a human body.
Complexity of Liver Transplants
Unlike heart and kidney transplants, liver transplants pose unique challenges due to the organ’s complex functions. The liver not only filters blood and removes toxins but also produces bile, regulates blood clotting, and processes nutrients. This makes it difficult to find a suitable animal organ replacement.
Pigs have emerged as the preferred donor species because their organs are anatomically and functionally similar to those of humans. However, due to the liver’s complexity, previous experiments involved attaching pig livers externally rather than transplanting them.
First Pig Liver Transplant
On March 10, 2024, Chinese doctors transplanted a liver from a genetically modified Bama miniature pig into a brain-dead adult. The pig liver had undergone six genetic modifications to reduce immune rejection. The transplant was an auxiliary procedure, meaning the patient’s original liver was left intact.
Over the 10-day experiment, researchers monitored key functions, including blood flow, bile production, and protein synthesis. The pig liver performed well, producing bile and albumin, an essential protein. However, it produced smaller amounts than a human liver, raising questions about whether it could fully replace a failing human liver.
A Bridge to Human Transplants
Doctors hope this type of transplant could serve as a “bridge organ,” temporarily supporting patients with severe liver failure while they wait for a human donor. Professor Peter Friend, a transplantation expert at Oxford University, described the results as “valuable and impressive” but emphasized that pig livers are not yet ready to replace human liver transplants. Instead, they could provide temporary support for patients in liver failure. Chinese researchers acknowledge that more research is needed. Dr. Lin Wang, one of the study’s authors, stated that future trials would focus on testing pig livers in living patients.
Global Efforts in Xenotransplantation
The success of pig liver transplantation follows other major advances in xenotransplantation. In recent years, U.S. surgeons have transplanted pig kidneys and hearts into a small number of patients, with mixed results. Some patients died within months, but others recovered and returned home.
In 2023, the University of Pennsylvania successfully attached a pig liver externally to a brain-dead patient, demonstrating that the organ could filter blood for at least 72 hours without severe complications. Meanwhile, a 53-year-old woman in Alabama received a genetically modified pig kidney in November 2024 and has since returned home. This marked a milestone in the field, showing that gene-edited pig organs can function inside the human body.
Ethical and Medical Challenges
Despite these advances, pig organ transplants face numerous challenges, including the risk of immune rejection, ethical concerns, and regulatory hurdles. The genetically modified pig liver used in the recent Chinese study had been altered to remove certain sugars that trigger immune responses and to introduce human-like proteins for better compatibility.
Another major question is whether a pig liver can fully replace a human liver. Some experts believe that pig livers could be useful as a short-term solution but may not be capable of sustaining life indefinitely.
Additionally, the ethical implications of xenotransplantation continue to be debated. While brain-dead patients have been used in these experiments, the eventual goal is to transplant pig organs into living patients, which raises concerns about safety and long-term effects.
Road Ahead
The Chinese research team has indicated that their next step is to transplant a pig liver into a living patient. They have also conducted another experiment where a brain-dead patient’s liver was completely removed and replaced with a pig liver, though details of that case have not been released.
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As global demand for organ transplants continues to grow, xenotransplantation offers a promising alternative. In the U.S. alone, more than 9,000 people are currently on the waiting list for a liver transplant. If pig livers can be developed to function effectively in humans, they could save thousands of lives.