The human liver is a fantastic organ with fantastic capabilities for regeneration. But each and every day, wear and tear along with disease of the liver can eventually produce irreversible harm to the organ.

When the liver does fail, the only alternative is frequently a transplant—but organs donated by willing donors are hopelessly short-supplied.

In a breakthrough, one team of Chinese researchers has studied another new alternative: pig livers. They published the very first results showing how a genetically engineered pig liver functioned inside a human subject this week.

A Genetically Engineered Solution

To outsmart the natural defenses of the body, the pig liver was gene-edited heavily prior to implantation. Researchers excised genes that normally provoke rejection and introduced human-like genes to enable the body to accept the organ as if it were one of its own.

The outcomes were promising. After a transplant of only two hours, the pig liver began secreting bile, a critical digestive juice responsible for breaking down fats. The organ also worked for 10 days with no alarming signs of inflammation or rejection.

This is the first time we experimented with determining whether pig liver can work well in the human body,” Xijing Hospital’s lead researcher, Lin Wang, said. Genetically modified pig livers, the study suggests, could serve as a temporary solution for waiting patients or patients whose own liver could grow back over time.

A New Era of Organ Transplants?

The shortage of donor organs available is a growing challenge. As of March 2025, more than 104,600 people wait on transplant lists, sometimes for months or decades. Sadly, many do not survive long enough to get them.

Xenotransplantation—transplantation from animal to human—may be a solution. Scientists have long considered pigs a wonderful source of transplanted organs due to the similarity of anatomy and function to humans. But there are still challenges to be overcome.

One of the biggest challenges is the immune system. Pig organs have sugars that human immune cells identify as foreign and attack. Pig organs also all contain porcine endogenous retroviruses (PERVs), which, although harmless to pigs, could potentially infect human cells.

In order to bypass these challenges, researchers have been employing gene editing technology to make pig organs more human-compatible. Some recent success includes:

• Pig hearts in baboons, which have kept the primates alive for over six months.
• Pig kidneys with 69 genetic changes, which were successfully used in monkeys.

Human pig kidney and heart transplantations, with mixed success. In 2021, doctors conducted a transplant of a pig kidney into a brain-dead patient, followed by more recent transplants into living patients—including a woman who recovered after receiving a pig kidney last year.

The Special Challenge of Liver Transplants

While xenotransplantation has been successful to some extent with hearts and kidneys, the liver is a more difficult nut to crack.

“The liver is so complex,” said Wang. This powerhouse organ is responsible for breaking down drugs, making enzymes to digest food, removing toxins, and controlling blood clotting. All of which are reliant on an incredibly sophisticated system of molecular interactions that might be species-specific.

A pig liver that doesn’t exactly match human biology may not be able to perform these essential tasks—or even worse, trigger destructive immune responses. That’s why this new research is so impressive—it provides the first real glimpse of how a pig liver would function in a human body.

The Future of Liver Xenotransplants

While this study is just in its beginning, it has good promise. If later studies confirm that genetically engineered pig livers are safe and work, they could serve as a temporary “bridge” for transplant patients awaiting a human organ.

Researchers are cautiously optimistic. “This research is a milestone in the history of xenotransplantation of the liver,” Iván Fernández Vega of Spain’s University of Oviedo said. “I found the research to be very relevant, but we have to be cautious.”

The better gene-editing technologies become and the way technology advances, the dream of having an infinite number of organs available for transplant could become a reality sooner.

For now, this experiment is a significant step towards solving the global shortage of organs.