The effect of collagenase on the formation of fibrous long spacing collagen aggregates.

In order to elucidate the close relationship between the formation of fibrous long spacing fibers (FLS) and collagenase activity, electron microscopic studies on the rat skin using tissue culture technique were performed. In culture of newborn rat skin, a large number of FLS was formed in the dermis in which activity of endogenous collagenase was markedly elevated. Ethylenediaminetetraacetic acid (EDTA) supplemented to the culture medium completely arrested the formation of the FLS; subsequent exposure to bacterial collagenase resulted in the appearance of FLS in the same fashion. In another set of experiments utilizing exogenous enzyme digestion with bacterial collagenase or chondroitinase ABC on skins of 1-day-old and 1-year-old rats, it was demonstrated that the FLS formed by incubation with bacterial collagenase were found only in the regions of the dermis where reticular fibers were identified by light microscopy. There was no effect of chondroitinase ABC on FLS formation. These studies indicate that the FLS are formed in the presence of elevated endogenous collagenase and might be derived from reticular fibers which are degraded by collagenase.