Genetically Modified Pig Lung Transplant Achieves Nine-Day Function in Human

A groundbreaking procedure saw a genetically modified pig lung successfully transplanted into a brain-dead human patient, functioning for nine days. This experiment highlights both the potential and the significant hurdles in the field of xenotransplantation.

During the trial, the patient began to show increasing signs of organ rejection, leading the medical team at the First Affiliated Hospital of Guangzhou Medical University in China to cease the experiment and allow the patient to pass away.

This marks the first instance of a pig lung being transplanted into a human, representing a notable advancement while also presenting new challenges that researchers will need to address as the field progresses.

The shortage of available human donor organs is a major issue for those in need of transplants. To tackle this problem, doctors are exploring xenotransplantation, which involves genetically modifying organs from non-human animals, primarily pigs.

The pig organs are not meant to be permanent fixes, but rather temporary solutions while patients wait for a suitable donor organ. Clinical trials involving pig kidneys and livers have shown promise, but more research is necessary.

Each type of organ presents its own intricacies. A surgical team led by Jianxing He at Guangzhou Medical University is now focusing on the complexities of lung transplants.

The objective of this experiment was not to achieve a flawless transplantation on the first attempt—though that would have been remarkable—but to study the patient’s immune system response to the introduced organ.

The patient, a 39-year-old man, was declared brain-dead following a brain hemorrhage, with his family providing written consent for the experiment.

The donor pig was a Bama miniature pig, genetically edited at six specific points to reduce the immune and inflammatory responses when introduced to the human body. This pig was kept in a controlled environment with stringent cleaning protocols.

In a meticulous surgical procedure, the left lung of the pig was placed into the patient’s chest cavity and connected to the airways, arteries, and veins. It’s worth noting that donor pigs typically do not survive major organ extraction, though the study does not specify the fate of the pig.

The patient was administered various immunosuppressants, which the researchers adjusted according to the patient’s condition over the course of the trial.

Initially, there were no immediate signs of hyperacute rejection, which was encouraging. However, within 24 hours post-transplantation, severe swelling was observed, likely due to the restoration of blood flow in that area.

Further complications arose due to antibody-mediated rejection on days three and six, leading to primary graft dysfunction—a critical lung injury that can occur within 72 hours of a transplant and is a leading cause of death among lung transplant patients. Although some recovery was noted by day nine, the experiment had reached its conclusion.

The lung is a particularly complex organ to transplant because it has direct exposure to the air. This necessitates a robust immune defense against airborne pathogens, utilizing multiple mechanisms.

The researchers managed to demonstrate that a pig lung can be successfully transplanted into a human without immediate hyperacute rejection, which is a crucial first achievement.

They acknowledged that the early onset of pulmonary edema emphasizes the need for strategies to prevent primary graft dysfunction in the future. “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,” the researchers noted.

They emphasize that by addressing these challenges, future studies can better approach lung xenotransplantation and move closer to practical applications. This research offers valuable insights into the immune, physiological, and genetic barriers that need to be overcome while paving the way for future innovations.

The findings were published in Nature Medicine.