Collagenase in keloid biopsies and fibroblasts

Trypsin-activated collagenase activity was analyzed in media from keloid biopsies as well as keloid fibroblasts using radiolabeled guinea pig skin collagen as a substrate for collagenase digestion. Collagenase activity per tissue dry weight and DNA was similar in keloid and normal dermal biopsies; however, it was significantly elevated in keloid compared to normal dermal fibroblast media. In two paired cell lines where keloid and normal dermal fibroblasts were isolated from the same patient, relative collagen synthesis and trypsin-activated collagenase were increased to a similar extent in the keloid cell lines compared to normals. The biopsy data are in agreement with other findings, and further confirm the hypothesis that increased collagen deposition in keloids does not result from decreased collagen degradation. In vitro, however, the data presented here indicate that in some cell lines increased collagen synthesis may be associated with increased trypsin-activated collagenase.