On Aug. 25, 2025, in a small step forward for the long-struggling field of xenotransplantation, surgeons in China have put a pig lung into a human. The man was brain-dead and the organ only lasted 9 days. But even human-to-human lung transplants are notoriously difficult, so the xenotransplant’s modest survival and brief period of functioning underscores the promise of organs from pigs that have been genetically edited to make their tissues more compatible with humans.

Described in Nature Medicine, the transplant was conducted at the First Affiliated Hospital of Guangzhou Medical University in May 2024. Surgeon Jianxing He and colleagues replaced the left lung of a 39-year-old man, who had suffered a catastrophic intracranial hemorrhage, with one from a pig. The lung functioned in its new home, delivering oxygen to the man’s blood and removing carbon dioxide. And its multiple genetic modifications enabled it to dodge an immediate immune response to foreign organs called a hyperacute rejection. Transplants, even if they’re human to human, often fail within hours because of this attack, which destroys blood vessels feeding the organ and lead to its collapse.

The lung fell prey to a later immune attack, however. Within 24 hours it had swollen with severe edema. Two days later, attacks by both antibodies and the complement cascade, another immune response, had damaged it. At the end of the 9 days, the pig lung was removed for analysis and the man was taken off life support per his family’s wishes. The experiment “clearly illustrates that lung xenograft survival in humans will require more genetic engineering and optimized immunosuppression,” says animal cloning specialist Dengke Pan, a co-author of the study and founder of Chengdu ClonOrgan Biotechnology, which makes the pigs.

The ultimate goal of xenotransplantation experiments is to use animal organs to eliminate the long waits now faced by patients needing new kidneys, hearts, lungs, livers, and pancreases.

After decades of struggle, however, xenotransplantation researchers are heartened by the progress with gene-edited pig kidneys. A kidney transplanted by an NYU Langone team lasted 4 months in a U.S. woman before it failed in April, and pig kidneys are still functioning in an unnamed woman in China who is 5.5 months postsurgery and a U.S. man, Timothy Andrews, whose kidney has lasted 8 months and is at his home in New Hampshire. “Wilma is doing her job,” Andrews says, referring to the name of the pig that the company eGenesis engineered for his kidney. Andrews may soon surpass the longest surviving xenotransplant, a chimpanzee kidney that in 1964 functioned in a Louisiana woman for 9 months.