Chinese scientists published a paper in the medical journal "Nature Medicine" on August 25, 2025, claiming that they have, for the first time in recorded history, transplanted a pig lung into the human body. The transplant was performed in Guangzhou in May 2024 on a brain-dead patient, but it lasted only a short time, with immune reactions observed for 9 days. Scientists told National Geographic that the reason for ending the experiment was "to achieve the main scientific objective of assessing whether there was uncontrolled infection or organ rejection," and also due to the family's request. Through this study, xenotransplantation, or cross-species organ transplantation, has reached another important milestone. The lung transplant followed recent attempts to transplant pig kidneys and hearts into humans.

The 39-year-old patient said that the lungs transplanted from a genetically modified pig did not immediately cause severe rejection, but he did experience an immune reaction and organ damage. Researchers stated that many "major challenges" remain before safely performing lung xenotransplantation in a medical setting, one of which is properly addressing the immune response.

"Verification should be conducted cautiously, and currently available evidence does not support clinical use in living patients," said the lead author He Jianxing to National Geographic. He said that more research, including long-term trials on brain-dead patients, should be conducted before considering clinical applications to reduce lung damage.

External experts said that this result is not particularly surprising, but it is an important step forward in the transplantation of pig organs to humans. "If we can determine safety and effectiveness, this could be a long-term paradigm shift," said Ankit Barratt, head of thoracic surgery at Northwestern Medicine.

In the United States, thousands of lung transplants are performed each year, and waiting times can be very long. At the same time, demand is growing, and transplant candidates may wait months or even years for a limited number of healthy, compatible human lungs, depending on their priority.

Additionally, Barratt pointed out that receiving organs from human donors "is like buying a used car," and "we don't know what we'll actually get," because the health and condition of donors vary greatly. He said that a stable supply of organs from healthy animals would allow for standardization of organ transplant quality, at least in theory.

Why is lung transplantation difficult?

Hospitals and biotechnology companies across the United States are already conducting clinical trials to transplant genetically modified pig hearts, livers, and kidneys into humans.

In 2024, the first attempt to transplant a genetically modified pig kidney into a living human body was made, but the patient Rick Suleiman died two months later. Another patient, Towana Rooney, had a pig kidney removed because it showed signs of rejection about four months after the transplant.

David Bennett became the first recipient of a genetically modified pig heart in 2022 and died two months later. The second case, Lawrence Fawcett, died six weeks after the operation in 2023.

Additionally, a genetically modified pig liver transplanted into a brain-dead patient in China in 2024 is believed to have functioned in the body for 10 days.

According to data from the U.S. Health Resources and Services Administration (HRSA), more than 100,000 people are currently waiting for organ donations in the United States, including thousands of patients who need lungs. According to experts, only about one-fifth of donor lungs are actually usable for transplantation.

"The five-year survival rate for lung transplants is the lowest, and the results are usually poor," said Brendan Keating, associate professor of surgery at NYU Langone Medical Center. In 2024, the medical center performed two pig kidney transplants on living patients, and since 2021, the center has conducted six pig kidney transplants on brain-dead patients.

However, experts say that lung transplants are much more complex than other organs. This is because the lungs play an important role in gas exchange with the surrounding environment and blood when exposed to pollutants. Barratt said that because the lungs are large in volume, they are also more prone to rejection compared to other organs.

"This is a positive study showing that such an attempt is actually possible," said Keating. However, many biological issues still need to be clarified before xenotransplantation from pigs to humans can be widely implemented. He pointed out that future studies must repeatedly test transplant responses in brain-dead patients, and the consent of families and guardians is crucial for this.

The authors of the paper also noted that several external factors may have influenced the results. Pigs were genetically modified to reduce the risk of rejection, and the patient was given a large amount of antibodies to suppress the immune response. The patient may have also had one lung remaining, which could have affected the immune response and the function of the donor lung.

Barratt said that the observation period of the study was too short to determine whether the body would reject the transplant. "Very short success, such as a few days of lung function, does not necessarily lead to long-term success." Nevertheless, he said, the transplant will help improve the scientific understanding of pig lung xenotransplantation.

Yoon Soo-hyun from the Center for Bioethics at Harvard Medical School said that while there may be benefits for human patients, keeping animals in laboratories solely for organs or using brain-dead patients who cannot express consent for experiments raises complex bioethical issues. "This decision is left to institutions and those responsible for ethical review."

Even if it is proven to be safe and effective for humans, xenotransplantation may eventually create a "two-tier system." This means that while some patients receive animal organs, others receive human organs. What happens if we find a quality difference between animal and human organs? Yoon said:

"If there is a 'second-best choice,' who would be transplanted into that 'second-best choice'?"

Original article: https://www.toutiao.com/article/1842061777850444/

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