EXTRACELLULAR-MATRIX CHARACTERIZATION DURING HEALING OF FULL-THICKNESS WOUNDS TREATED WITH A COLLAGEN ELASTIN DERMAL SUBSTITUTE SHOWS IMPROVED SKIN REGENERATION IN PIGS/

We investigated the architecture of the extracellular matrix (ECM) dur ing healing of full-thickness wounds in the pig, Two different treatme nts, one based on epidermal transplantation (split skin mesh grafts, S P wounds) and one consisting of a combination of epidermal transplanta tion and a dermal matrix substitute (MA wounds) were compared, The der mal matrix consisted of native bovine collagen coated with elastin hyd rolysate, The latter treatment reduced wound contraction and improved tissue regeneration. The expression patterns of fibronectin, von Wille brand factor, laminin, chondroitin sulfate, and elastin, detected by i mmunohistochemistry, were examined in time and indicated different sta ges of healing. During the early phase of healing the dermal matrix in duced more granulation tissue, a different fibronectin expression patt ern, and rapid vascular cell ingrowth (von Willebrand factor), Further more, in the MA wounds chondroitin sulfate was detected earlier in the basement membrane and fibronectin staining disappeared more rapidly, During later stages of healing, chondroitin sulfate expression was sel ective for areas in which ECM remodeling was active; in these specific areas elastin staining reappeared. ECM remodeling and elastin regener ation occurred both in the upper and lower dermis for the MA wounds bu t only in the upper dermis for the SP wounds, Electron microscopic eva luation of the wounds after 2 weeks showed many myofibroblasts in the SP wounds, whereas in the MA wounds cells associated with the dermal m atrix had characteristics of normal fibroblasts, The results suggest t hat the biodegradable dermal matrix served as a template for dermal ti ssue regeneration, allowed faster regeneration, and improved the quali ty of healing in large full-thickness skin defects.