Pig Lung Transplanted Into a Human in Major Scientific First

A genetically modified pig lung has been transplanted into a brain-dead human recipient and maintained function for nine days-an advance that highlights both the potential and the substantial hurdles of xenotransplantation.

During the study, clinicians observed progressively stronger indicators of organ rejection. Scientists at the First Affiliated Hospital of Guangzhou Medical University in China ultimately brought the trial to an end, after which the recipient was allowed to die.

This marks the first reported instance of a pig lung being transplanted into a human, representing a meaningful leap forward while also surfacing fresh challenges for researchers working to advance this developing clinical approach.

Why xenotransplantation is being pursued

A shortage of suitable human donor organs remains a major constraint for people who require transplants. To ease this bottleneck, clinicians have been exploring xenotransplantation: using organs from non-human animals-primarily pigs-after genetic modification.

These genetically modified pig organs are not designed as lifelong replacements. Instead, they are intended as a stopgap “bridge” to support patients until a human donor organ becomes available. Early clinical trials involving pig kidneys and livers have been encouraging, though additional research and refinement are still required.

Because every organ comes with its own distinct technical and biological difficulties, a team led by surgeon Jianxing He at Guangzhou Medical University turned to one of the toughest remaining targets: lungs.

Genetically modified pig lung transplant: patient, donor, and aims

The purpose of this first attempt was not to achieve an immediate, definitive success-an outcome that would have been remarkable but not a realistic expectation. Rather, the researchers set out to monitor how the recipient’s immune system would react to the transplanted lung.

The recipient was a 39-year-old man who, after suffering a brain haemorrhage, was declared brain-dead following four separate clinical assessments. Written informed consent for participation was provided by his family.

The donor animal was a so-called six-gene-edited pig: a Bama miniature pig that had undergone six CRISPR gene edits and was kept in an isolated facility with stringent disinfection procedures. The genetic changes were aimed at reducing the recipient’s immune and inflammatory reactions.

In a carefully executed operation, the pig’s left lung was implanted into the recipient’s chest and connected to the airways, arteries and veins. The paper does not state what happened to the donor pig, though pigs generally do not survive the removal of a major organ.

Alongside the transplant, the patient received multiple immunosuppressants, with dosing adjusted by the research team in response to physiological changes observed over time.

What happened during the nine-day experiment

At the outset, there were no immediate signs of hyperacute rejection during the critical hours after surgery. By 24 hours post-transplant, however, pronounced swelling (oedema) was detected-potentially linked to reperfusion as blood supply returned to the transplanted tissue.

On days three and six, antibody-mediated rejection inflicted further injury. This led to primary graft dysfunction: a severe form of lung injury that arises within 72 hours of transplantation and is the leading cause of death among lung transplant patients. Although there were indications of recovery by day nine, the study was concluded.

Why lungs are especially challenging in xenotransplantation

Lungs are among the most complex organs to transplant because they are directly exposed to outside air. They must therefore serve as an immediate frontline barrier against airborne particles and pathogens, and they possess multiple pathways for mounting immune responses.

Even so, the team demonstrated that a pig lung can be transplanted into a human in a manner that avoids hyperacute rejection-an important early milestone.

"The early onset of pulmonary edema underscores the importance of preventing primary graft dysfunction in future xenogeneic lung transplantation," the researchers write in their paper.

"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.

"By addressing these challenges, future studies can refine the approach to lung xenotransplantation and move closer to clinical translation. This study provides crucial insights into the immune, physiological and genetic barriers that must be overcome, and paves the way for further innovations in the field."

The research has been published in Nature Medicine.