Effect of Cultured Dermal Substitute Composed of Collagen Sponge Seeded with Fibroblasts in Simultaneous Skin Graft Overlay

Abstract

An artificial dermal substitute composed of a xenogenous collagen sponge has been widely used to create a dermal component in a full-thickness skin wound. However, one of the disadvantages in using the dermal substitute is that it requires a 2-stage surgical procedure for final wound closure. In order to close the wound much more rapidly, another type of dermal substitute which enables a simultaneous skin graft overlay is needed. In the present study, we investigated the effect of a collagen sponge seeded with isogenic fibroblasts on a simultaneously overlaid skin graft in a rat model. Normal dermal fibroblasts of SD rat were seeded and cultured on a collagen sponge composed of cross-linked porcine type I collagen. Full-thickness skin wounds were created on the dorsum of SD rats. The collagen sponges with or without fibroblasts were placed in the wounds, then covered simultaneously with split-thickness skin graft (STSG) , At 1 week and 4 weeks after grafting, overlaid STSG survival TGF-β1 level, wound contraction, final re-epithelization and histology of the grafts were studied. The overlaid STSG survived moderately but the seeded fibroblasts did not enhance the STSG survival rate. Also, there were no significant differences in wound contraction and in the final wound epithelization between the collagen sponge seeded with and without fibroblasts. Both collagen sponges with and without fibroblasts developed neo-dermal structure without any specific immunological reaction. However, the fibroblast-seeded collagen sponge grafts showed significant re-epithelization along the junctional surface between the collagen sponge and the STSG by out-growing of the hair follicle cells. This epithelization seemed to result in formation of epithelial inclusion cysts in the neo-dermis. It was suggested that the seeded fibroblasts strongly induced such an epithelial outgrowth. The cultured collagen sponge may have beneficial effect on re-epithelization in a certain type of simultaneous skin graft overlay such as meshed STSG.