Transplanted acellular allograft dermal matrix. Potential as a template for the reconstruction of viable dermis

The use of allograft donor skin as a permanent skin transplant in full-thickness burns is limited by its immunogenic properties and by the inappropriateness of immunosuppression of a burn patient. Allograft skin will initially take on a full-thickness wound, but it is ultimately rejected. This immunogenic response to allograft skin is directed primarily against the cells of the epidermis and the endothelial cells in the dermis. To date, it has not been possible to remove these immunogenic cells while maintaining the integrity of the nonimmunogenic components of allograft dermis. In this study, we have investigated a method of processing porcine skin to produce an acellular, structurally intact, dermal matrix. We have developed a process that de-epidermizes and decellularizes fresh porcine skin, while maintaining the basement membrane complex and the extracellular matrix structure of the dermis. Porcine dermis processed by this method was initially assessed for toxicity in a rat subcutaneous implant study. In vivo assessment confirmed the absence of local and systemic toxicity. Subsequently, we investigated the potential use of this matrix in combination with a meshed split-thickness autograft (STSG) as a permanent allograft in full-thickness wounds in pigs. Histological analysis revealed that the dermal matrix supported fibroblast infiltration, neovascularization, and keratinocyte migration from an overlying STSG. There was no evidence of an inflammatory cell infiltrate or a cell-mediated immune response. This apparent lack of an immune response was also tested in vitro by assessing recipient lymphocyte proliferation in response to an extract of the dermal matrix. These results suggest that skin processed by this method has the potential to be used as a permanent dermal allograft to augment the performance of an STSG in the closure of full-thickness wounds.