Collagen and Mucopolysaccharides in the Hypertrophic Scar

Abstract

The hypertrophic scar occurs in healed skin from deep burns or equivalent injury in humans. It is erythematous, elevated, hard to the touch, and can produce severe contractures. This scar is characterized by marked increases in collagen and chondroitin-4-sulfate. Transmission electron microscopy, including localization of ruthenium red, scanning electron microscopy and appropriate biochemical assays have served to evaluate the relationship between collagen and interstitial mucopolysaccharide material in the hypertrophic scar. These results have been compared to those obtained for normal skin, mature scar, and granulation tissue, and are interpreted from the standpoint of explaining some of the clinical aspects of the scar. Two basic forms of interstitial material are observed, globular and filamentous. The globular forms predominate in normal skin, mature scar and granulation tissue. Hypertrophic scar demonstrates a marked dominance of the filamentous forms, which often appear to link collagen in chain-like fashion. Scanning electron microscopy complements this view by demonstrating a near homogeneous dermal matrix, as if the collagen filaments were “glued” together. In mature scar, this dermal mass appears to be resolving into individual collagen filaments. Globular forms of the interstitial material can be demonstrated in hypertrophic scar if the tissue is stretched and held in position from 1 to 3 hours prior to fixation. However, no change in chondroitin-4-sulfate is observed. In the stretch condition individual collagen filaments are observed. It is suggested that one of the factors generating the rigid character of the hypertrophic scar may be a firm intercollagen linkage mediated by chondroitin-4-sulfate.