Burn specialists at Massachusetts General Hospital (MGH) in Boston have successfully used a live-cell, genetically engineered pig skin xenograft to temporarily close a burn wound on a human patient, marking the first time that tissue derived from an animal with gene edits has been directly transplanted onto a human wound.
The procedure was part of a US FDA-cleared phase one clinical trial, which was led by surgeon Dr. Jeremy Goverman of MGH’s Summer Redstone Burn Service.
In a press release from the hospital, the authors note that while human cadaveric allografts obtained from skin banks is the standard of care for temporarily closing large, deep second- and third-degree burn wounds, there are often shortages of this material. As well, cadaveric allografts are expensive and require strictly regulated tissue banks.
The pigs used in this study were developed at MGH in the 1990s by Dr. David Sachs, and lack a gene specific to pigs, the removal of which allows the tissue to appear less foreign to the human immune system. Boston-based company XenoTherapeutics designed and implemented the safety protocols for the live tissue graft.
During the procedure, a 5-by-5-centimetre piece of genetically engineered pig skin was placed on the recipient’s burn wound that had been cleared of necrotic tissue. The pig skin graft was placed next to a much larger piece of cadaveric skin, for comparison. Both grafts were secured with surgical staples and gauze bandages.
Five days post-graft, surgeons removed the temporary cadaveric skin and xenograft. According to the release, both skin grafts were adherent to the underlying wound bed and appeared indistinguishable from each other.
Additionally, no adverse events were further observed or reported and the wound was then treated further with a skin graft harvested from the patient’s own thigh. Since then, healing of the wound has progressed as the surgeons anticipated, and the patient is expected to be able to return to work shortly.
An independent safety review found no transmission of porcine endogenous retroviruses (PERVs), which had previously represented a theoretical roadblock for the transplantation of pig tissues or organs into human recipients.
“It is not the trial itself that is so mind-boggling and intriguing to me; rather, it’s what this trial represents,” said Dr. Goverman, in the release. “This small step we took today, represents a massive number of hours spanning decades of research in a multitude of fields including transplantation biology, immunology and genetic engineering.”
“Additionally, rapid advancements in gene-editing technology open a vast new avenue for genetically modifying pig skin that is not rejected, representing the next chapter in standards of care for burn and transplant patients alike,” he said.
The research team plans to replicate similar effective outcomes in additional patients in the coming months.