A Chinese patient who was on the brink of death from worsening liver function endured for three days with a pig liver before receiving a liver transplant. An animal organ with some genes altered to block immune rejection served as a bridge to extend life until a transplant organ could be secured.
The international journal Nature said on the 6th (local time) that a medical team at Xijing Hospital of Air Force Medical University in Xi'an, China, connected an extracorporeal circulation device containing a pig liver to a patient with liver failure and kept the patient alive until an actual liver transplant surgery.
According to Dr. Lin Wang, the surgeon who led the operation, the 56-year-old man suffered severe liver damage due to hepatitis B, other liver diseases, and alcohol, and his liver function had rapidly deteriorated. The patient underwent extracorporeal circulation using a pig liver, received a donated liver in January, and is currently recovering.
◇A pig liver filters blood outside the body
The Chinese researchers performed two surgeries to save a patient in liver failure whose liver was no longer functioning properly. First, they connected the patient's blood to an extracorporeal liver circulation device located outside the body. Inside the device was a pig liver with genes edited with CRISPR-Cas9 to prevent immune rejection. CRISPR-Cas9 is an enzyme complex that cuts specific genes from DNA and replaces them with others.
The medical team connected a tube to a vein in the patient's leg and linked it to the extracorporeal circulation device containing the pig liver. The pig liver removed harmful waste from the patient's blood circulated by a pump. The blood was then returned to the body. The team said the pig organ did not trigger immune rejection and the patient's native liver also began to improve. After three days, the patient was separated from the extracorporeal circulation device to prevent the risk of infection or complications. The actual liver transplant surgery took place a few days later.
Experts said the results show that xenotransplantation using other animals could solve the chronic shortage of organ donations. Even if animal organs cannot fully replace human organs, they can buy time until a transplant organ is found and help damaged organs recover. It is, in effect, a bridge to an actual human organ transplant. The fact that the patient's liver function was maintained after separation from the extracorporeal device, unlike before, supports this. The Xijing Hospital team said it will compile the surgical results and publish them in an international journal.
Earlier, on Feb. in the United States, a University of Pennsylvania medical school team reported in the international journal "Nature Medicine" that extracorporeal circulation using a pig liver succeeded in a brain-dead donor. The team built an extracorporeal circulation device with a gene-edited pig liver and connected it to the blood vessels of four brain-dead donors. Extracorporeal circulation succeeded for 72–84 hours in three. In one case, the team stopped extracorporeal circulation midway and performed a liver resection. When they resumed extracorporeal circulation, the liver produced bile, indicating functional recovery.
◇Pig heart, kidney, lung, and liver transplants
Xenotransplantation has shown results across various fields. At least 12 people in the United States and China have received transplants of pig organs such as the heart, kidney, liver, and thymus. In Nov. last year, Massachusetts General Hospital (MGH) under Harvard Medical School announced that a 67-year-old man who had undergone dialysis for more than two years due to renal failure lived for a record 271 days without dialysis after receiving a genetically modified pig kidney.
In Aug. last year, the world's first case emerged in which a gene-edited pig lung was transplanted into a person and functioned for nine days. A team led by Dr. He Jianxing at the First Affiliated Hospital of Guangzhou Medical University in China, together with researchers from Korea, Japan, and the United States, reported in Nature Medicine that a left lung from a gene-edited pig was transplanted into a brain-dead donor and functioned for nine days.
Results in pig liver transplantation have also followed in China. In Oct. last year, a study reported that a 71-year-old male liver cancer patient who received a pig liver transplant survived for 171 days. Earlier in March, the Xijing Hospital team performed the first pig-to-brain-dead human liver transplant, but this was the first time it had been transplanted into a living person.
Xenotransplantation has yet to be proven fully safe. In Jan. 2022, the University of Maryland medical school transplanted a gene-edited pig heart into a person. The 57-year-old American man who underwent the surgery died of complications two months later. The following year, a pig heart was transplanted again into a 58-year-old patient, who also died within six weeks due to immune rejection.
Scientists are trying to edit pig organ genes to prevent immune rejection. In parallel, some researchers are blocking the genes that form specific organs in pig embryos (fertilized eggs) and inserting human embryonic stem cells. The idea is to grow human organs in pigs. A team led by Dr. Liangxue Lai at the Guangzhou Institute of Biomedicine and Health in China said at the International Society for Stem Cell Research in Hong Kong in July last year that pig embryos with human hearts survived for 21 days and showed heartbeats during that time.
Extracorporeal circulation research is considered the fastest to commercialize in xenotransplantation. Permanently transplanting animal organs or cultivating human organs in animals raises not only safety issues but also bioethics controversies. In contrast, extracorporeal circulation is used temporarily before human organ transplantation, so side effects and ethical concerns are comparatively smaller. Last year, the U.S. Food and Drug Administration (FDA) approved a clinical trial to test whether extracorporeal circulation using a gene-edited pig liver can safely treat patients with organ failure.
References
Nature Medicine (2026), DOI: https://doi.org/10.1038/s41591-025-04196-3
Journal of Hepatology (2025), DOI: https://doi.org/10.1016/j.jhep.2025.08.044
Nature (2025), DOI:https://doi.org/10.1038/s41586-025-08799-1
Nature Medicine (2025), DOI: https://doi.org/10.1038/s41591-025-03861-x