Expression of type VI collagen mRNA during wound healing

During the highly regulated process of wound healing the expression of the interstitial collagens I and III is increased in a time-dependent fashion. Although ultrastructural and in vitro studies suggest a physiologic role of collagen VI in the organization of extracellular matrix deposition, nothing is known about its role in wound healing. Therefore, we studied collagen VI gene expression during wound healing in humans compared to that of collagens I and III. The presence of specific alpha 1(VI) and alpha 3(VI) mRNA species in scar tissue was demonstrated by Northern blot analysis. Quantification of mRNA expression by dot blot analysis and in situ hybridization indicated that like for the interstitial collagens I and III collagen VI gene expression was increased during wound healing, reaching its maximum 2 weeks after initial insult. In the late phase of wound healing like alpha 1(I) the alpha 1(VI) gene expression was not down regulated significantly. In contrast, a reduction of alpha 3(VI) collagen gene expression was observed, as was for the alpha 1(III) collagen gene, indicating a non-coordinate regulation of these chains. Collagen VI gene expression could be localized to fibroblast-like cells and to endothelial cells of newly formed vessels. Collagen VI gene expression was undetectable in smooth muscle cells and myoepithelial cells of eccrine glands. These results indicate that collagen VI gene expression is regulated in a time-dependent fashion and that fibroblasts and endothelial cells appear to play an important role in collagen VI synthesis during wound healing.