Vascularized composite allograft (VCA) transplantation can restore form and function following severe craniofacial injuries, extremity amputations or massive tissue loss. The induction of transplant tolerance would eliminate the need for long-term immunosuppression, realigning the risk–benefit ratio for these life-enhancing procedures. Skin, a critical component of VCA, has consistently presented the most stringent challenge to transplant tolerance. Here, we demonstrate, in a clinically relevant miniature swine model, induction of immunologic tolerance of VCAs across MHC barriers by induction of stable hematopoietic mixed chimerism. Recipient conditioning consisted of T cell depletion with CD3-immunotoxin, and 100 cGy total body irradiation prior to hematopoietic cell transplantation (HCT) and a 45-day course of cyclosporine A. VCA transplantation was performed either simultaneously to induction of mixed chimerism or into established mixed chimeras 85–150 days later. Following withdrawal of immunosuppression both VCAs transplanted into stable chimeras (n =4), and those transplanted at the time of HCT (n =2) accepted all components, including skin, without evidence of rejection to the experimental end point 115–504 days posttransplant. These data demonstrate that tolerance across MHC mismatches can be induced in a clinically relevant VCA model, providing proof of concept for long-term immunosuppression-free survival.
Background
The current standard of care for burns requiring operative treatment consists of early burn excision and autologous split-thickness skin grafting. However, in large burns, sufficient donor sites may not be available to achieve total coverage, necessitating temporary coverage with allogeneic human cadaver skin grafts or synthetic skin substitutes. A previous study from this laboratory demonstrated that skin grafts from alpha-1,3 galactosyltransferase knockout (GalT-KO) miniature swine enjoyed survival comparable to that of allogeneic skin grafts in baboons.
Methods
In the present study, we have evaluated the immune response against sequential GalT-KO and allogeneic skin grafts to determine whether such serial grafts could extend the period of temporary wound coverage before definitive grafting with autologous skin.
Results
We report that rejection of primary GalT-KO skin grafts led to an anti-xenogeneic humoral response with no evidence for sensitization to alloantigens nor acceleration of rejection of allogeneic skin grafts. Similarly, presensitization with allogeneic skin did not lead to accelerated rejection of xenogeneic skin.
Conclusions
These data suggest that GalT-KO skin grafts could provide an early first-line treatment in the management of severe burns that would not preclude subsequent use of allografts, and that serial grafting of GalT-KO skin and allogeneic skin could potentially be used to provide an extended period of temporary burn wound coverage.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.