Type V collagen in experimental granulation tissue

To evaluate the spatial and temporal expression of type V collagen in a wound healing model, subcutaneously implanted viscose cellulose sponges in rats were used to induce granulation tissue formation. Analyses on granulation tissue were carried out on days 3, 5, 8, 14, 21, 30, 59 and 84. Acid soluble collagens were extracted and the relative amount of type V collagen was quantified by SDS-PAGE. Specific antibodies to type I, III and V collagens were used in immunohistochemistry and specific RNA probes to proalpha1(I), proalpha1(III) and proalpha1(V) collagen in in situ hybridization. Type V collagen content increased relative to type I and III collagens up to day 8 and remained at the same level for up to the three months. Type V collagen was expressed strongly in blood vessel walls as seen in immunohistochemistry. In situ hybridization showed that all of the three types of collagen were expressed mostly in fibroblast-like cells and also in rounded cells, especially type V collagen. In conclusion, type V collagen was seen in the wound healing model in increasing amounts from day 3 onwards, its localization being highly associated with blood vessels in granulation tissue and it was synthesized by fibroblast-like and rounded cells.