INCREASED TYPE-I AND TYPE-III COLLAGEN AND TRANSFORMING GROWTH-FACTOR-BETA-1 MESSENGER-RNA AND PROTEIN IN HYPERTROPHIC BURN SCAR

Hypertrophic scar is the result of abnormal healing that often follows thermal injury. Hypertrophic scar is characterized by excessive derma l fibrosis and scarring. Five cases of human hypertrophic scar were co mpared with normal skin using in situ hybridization to localize mRNAs for procollagen types I and III and transforming growth factor-beta 1. Expression of type I procollagen and TGF-beta 1 were also examined wi th immunohistochemistry. The results demonstrated a significant increa se in the expression of mRNA for types I and III procollagen and type I procollagen protein by fibroblasts in hypertrophic scar compared wit h normal skin. In all cases of hypertrophic scar, significant numbers of cells expressed TGF-beta 1 mRNA or peptide. Neither TGF-beta 1 mRNA nor protein was detected in control tissues. These results suggest a profound increase in production and expression of types I and III coll agen mRNA by the fibroblasts in hypertrophic scar. This may result fro m increased TGF-beta 1 production, through paracrine and autocrine pat hways, as have been described for this fibrogenic cytokine.