In a groundbreaking medical achievement, surgeons have successfully transplanted a lung from a genetically modified pig into a brain-dead human recipient for the first time. This remarkable procedure was reported to have functioned effectively for nine days, marking a significant advancement in the field of xenotransplantation. This innovative technique aims to address the pressing global organ shortage crisis, which, according to the World Health Organization, meets only up to 10% of the worldwide demand for organ transplants.
Despite the promising results, experts caution that there is still a considerable journey ahead before pig lungs can be used in living patients. Dr. Justin Chan, a lung transplant surgeon at the NYU Langone Transplant Institute, described the study as “exciting and promising work,” but he emphasized that it pertains to a single patient and is classified as a “qualified success.” He noted, “These lungs are not able to independently sustain a patient,” highlighting the need for further research.
Andrew Fisher, a professor of respiratory transplant medicine at Newcastle University, echoed Dr. Chan's sentiments. He stated, “This work is very welcome in furthering our understanding, but it marks an incremental step forward. There is much more work required and we are not on the dawn of an era of lung xenotransplantation using pig lungs.”
Xenotransplantation has gained momentum in recent years, with various organs, including hearts, kidneys, and livers, being transplanted from pigs into humans. This process involves genetically modifying pigs by removing specific pig genes and inserting human genes to minimize the rejection of the organs by the recipient's immune system. Initial studies are often conducted on brain-dead human recipients before further advancements are made towards living patients.
While there have been a few cases of living recipients, many have faced significant challenges, with numerous individuals passing away within weeks or months post-surgery, though not always due to transplant-related complications. On a more positive note, some patients with transplanted pig kidneys have survived with functioning organs for several months after their procedures.
Experts assert that xenotransplantation of lungs presents unique challenges. Fisher noted, “Every breath you breathe in is bringing the external environment into the body.” This characteristic necessitates that the lungs be exceptionally adept at responding to various attacks from pollution, infections, and other environmental factors. Consequently, the immune system in the lungs is highly sensitive and active, posing additional challenges for successful organ transplantation.
In a study published in the journal Nature Medicine, researchers from China detailed their pioneering work in which they transplanted the left lung from a genetically modified Chinese Bama Xiang donor pig into a 39-year-old brain-dead male recipient. Remarkably, the lung remained viable and functional for a 216-hour period without triggering hyperacute rejection—a rapid, aggressive immune response from the recipient's body. Additionally, there were no indications of infection during this time.
However, 24 hours post-transplantation, the lung exhibited signs of fluid accumulation and damage, likely due to transplant-related inflammation. Despite the recipient receiving powerful immunosuppressive medication, the transplanted organ faced progressive attack from antibodies, leading to significant damage over time. Fisher explained, “The impact of the damage was likely underestimated because the human recipient still had one of their own lungs present, which would have compensated for the damaged porcine lung.”
Professor Peter Friend from the University of Oxford noted that the results were complicated by the acute inflammatory state caused by brain death itself, which could have influenced some of the observed effects. The researchers acknowledged the need for further refinement in their approach, stating, “Continued efforts are needed to optimize immunosuppressive regimens, refine genetic modifications, enhance lung preservation strategies, and assess long-term graft function beyond the acute phase.”
In addition to xenotransplantation, Friend pointed out that alternative strategies are being explored to increase the availability of organs. This includes remodeling donor organs with stem cells and investigating the potential of growing humanized organs inside pigs or sheep. Fisher added that while xenotransplantation for lungs shows promise, another viable approach is to rehabilitate human donor lungs deemed unsuitable for transplantation, enabling their use in patients. “If we get that right, that’s something that can be implemented within months, and certainly in years could be making very big differences,” he concluded.
