A genetically modified pig lung was transplanted into a brain-dead man and functioned for nine days, the surgery in China being the first of its kind in the world.
CNN reports that there has been some recent success transplanting pig kidneys and hearts into people, but this is believed to be the first attempt to transplant a pig lung into a human.
Doctors hope it might be an option for people needing organs at some stage in the future, but experts believe it won’t be any time soon.
Authors from Guangzhou Medical University First Affiliated Hospital in China didn’t identify the patient in the study, but he’s described as a 39-year-old man who was declared brain dead after a brain haemorrhage.
The medical team transplanted a pig lung into his body after getting consent from his family. The findings were published in the journal Nature Medicine.
With any human-to-human transplant or animal-to-human transplant –xenotransplantation – doctors watch carefully for infection and rejection.
The patient received several medications to reduce the risk of infection and rejection, while the lung itself had also received six gene edits, and the donor pig was kept in an extremely clean and strictly controlled area for its entire life.
The researchers reported that they didn’t see immediate signs of rejection after the transplant but problems arose after just a day.
Widespread swelling developed throughout the man’s body as fluid built up in his tissues, potentially due to a blood flow problem.
There were some signs of partial recovery just days after the transplant, but despite all the precautions, doctors saw signs that the man’s body was starting to reject the organ.
At the request of the patient’s family, doctors terminated the experiment.
“Although this study demonstrates the feasibility of pig-to-human lung xenotransplantation, substantial challenges relating to organ rejection and infection remain,” the researchers wrote, concluding that more research is needed before the procedure could be repeated in a clinical trial.
Valves
Pig valves have been transplanted into humans for the past 30 years; organs are trickier, but doctors have seen limited success with genetically modified pig hearts and pig kidneys. They’ve also experimented with a genetically modified pig liver but had less success, at least so far.
The most success to date has been with a man in Massachusetts, Tim Andrews, who is living with a genetically modified pig kidney that was transplanted in January.
Experts say there’s a way to go before pig lung transplants show as much success.
“Nobody would sign up for a nine-day lung transplant,” said surgeon Adam Griesemer, a senior member of the xenotransplantation team for NYU Langone’s Transplant Institute, who was not involved with the new research.
He said transplants of pig lungs into other animal in past experiments have shown similar results.
“I think it is very important to do these studies since you can’t assume that the animal models are going to perfectly reflect what happens in human recipients,” he added.
The researchers in China said they did the study, in part, because there is “transformative potential” in xenotransplantation.
Dr Ankit Bharat, Chief of Thoracic Surgery and Director of the Northwestern Medicine Canning Thoracic Institute, found the research interesting but added that pig-to-human lung transplants are unlikely to be happening any time soon.
“We’ll learn something from this, but I’m not fully convinced it is really opening the doors to doing bigger trials, just based on what we observed here,” he said.
Lungs are much more complicated to transplant than organs like kidneys, he said.
They play a critical role in blood filtration, temperature regulation, platelet production, pH balance and immune defense, and they have metabolic and endocrine functions. And unlike the kidney or heart, lungs are exposed to outside elements like viruses and bacteria when they take in air.
Because they are so large and covered with proteins that aid in immune defence, even with a lung transplant from another human, it’s difficult to circumvent the body’s instinct to reject something foreign, Bharat said.
“That’s a tough problem to solve. We haven’t really solved that, even in human organs,” he said. “So you are just adding another layer of complexity with pig antigens that can become another problem.”
Although the researchers behind the new study suggested the man’s body did not show signs of immediate rejection of the pig lung, Bharat said he wasn't so sure, after looking at the X-ray images and CT images.
“There is a lot of damage, and I don’t know if I’m fully convinced that there was no hyper-acute rejection.”
At least where lung transplants are concerned, Bharat added, advances in the use of a human’s own stem cells may be more promising than transplanting a pig organ.
Griesemer said there was also research under way to use a pig lung as a scaffold so scientists using stem cell therapy can swop out the pig cells for human cells.
“In a sense, that would not really be a xenotransplant, because the cells would be human, but the structure would be from a pig,” Griesemer said. “So that’s another possibility for how medical technology might solve this problem for people needing lung transplants.”
Study details
Pig-to-human lung xenotransplantation into a brain-dead recipient
Jianxing He, Jiang Shi, Chao Yang et al.
Published in Nature Medicine on 25 August 2025
Abstract
Genetically engineered pig lungs have not previously been transplanted into humans, leaving key questions unanswered regarding the human immune response in the context of a xenotransplanted lung and the possibility of hyperacute rejection. Here, we report a case of pig-to-human lung xenotransplantation, in which a lung from a six-gene-edited pig was transplanted into a 39-year-old brain-dead male human recipient following a brain haemorrhage. The lung xenograft maintained viability and functionality over the course of the 216 hours of the monitoring period, without signs of hyperacute rejection or infection. Severe edema resembling primary graft dysfunction was observed at 24 hours after transplantation, potentially due to ischaemia–reperfusion injury. Antibody-mediated rejection appeared to contribute to xenograft damage on postoperative days 3 and 6, with partial recovery by day 9. Immunosuppression included rabbit anti-thymocyte globulin, basiliximab, rituximab, eculizumab, tofacitinib, tacrolimus, mycophenolate mofetil and tapering steroids, with adjustments made during the postoperative period based on assessments of immune status. Although this study demonstrates the feasibility of pig-to-human lung xenotransplantation, substantial challenges relating to organ rejection and infection remain, and further preclinical studies are necessary before clinical translation of this procedure.
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Chinese team reports xenotransplant and first-step liver experiment
Second person to receive transplanted pig kidney dies
First combined heart pump and pig kidney transplant