REGENERATION OF FULL-THICKNESS WOUNDS USING COLLAGEN SPLIT GRAFTS

Collagen-based skin substitutes are among the most promising materials to improve regeneration of full-thickness wounds. However, additional meshed grafts or cultured epidermal grafts are still required to crea te epidermal regeneration. To avoid this, we substituted collagen-base d split grafts, i.e., grafts with a separated top and bottom layer, in a rat full-thickness wound model and compared regeneration with nontr eated, open control wounds. We hypothesized that epidermal regeneratio n would occur in the split in between the two layers, with the top lay er functioning as a clot/scab and the bottom layer as a dermal substit ute. Two types of dermal sheep collagen (DSC) split grafts were tested : one with a top layer of noncrosslinked DSC (NDSC) and bottom layer o f hexamethylenediisocyanate crosslinked DSC (HDSC), further called N/H DSC; and the second with both a top and bottom layer of HDSC (H/HDSC). With the N/HDSC split graft NDSC did not function as a sponge for for med exudate and as a consequence the split was no longer available to facilitate epidermal regeneration. In contrast, with the H/HDSC graft the split facilitated proliferation and differentiation of the epiderm al cells in the proper way. With this graft, clot formation was restri cted to the top layer, which was rejected after 8 weeks, while the bot tom layer functioned during gradual degradation as a temporary matrix for the formation of autologous dermal tissue. H/HDSC strongly inhibit ed infiltration of myofibroblasts, resulting in a 30% wound contractio n, while a 100% contraction was found with the open control wound. The results show that H/HDSC split-grafts function conforms to the hypoth esis in regeneration of large, full-thickness wounds without further a ddition of seeded cells or use of meshed autografts. (C) 1995 John Wil ey & Sons, Inc.