Hypertrophic scar fibroblasts accelerate collagen gel contraction

Excessive contraction of hypertrophic scar and subsequent contracture formation are a formidable problem after thermal injury. A comparison between fibroblasts from hypertrophic scar and normal skin was made with the use of fibroblast‐populated collagen lattices as a measure of cellular generated contractile forces. Hypertrophic scar and normal skin fibroblasts were mixed with soluble tendon collagen and Dulbecco's modified Eagle medium supplemented with 10% serum, and contraction was measured by serial area measurements. Parallel experiments in the presence of transforming growth factor‐β or anti‐transforming growth factor‐β antibody examined the role of this cytokine on lattice contraction. Transforming growth factor‐β activity was measured in an additional set of 10 biopsy specimens. Hypertrophic scar fibroblasts contract lattices at a significantly faster rate than do normal skin fibroblasts. Exogenous transforming growth factor‐β increased lattice contraction by normal skin fibroblasts but had little effect on hypertrophic scar cell‐populated lattices. The addition of anti‐transforming growth factor‐β antibody decreased lattice contraction by both cell types. Transforming growth factor‐β activity was significantly increased in the hypertrophic scar biopsy specimens. Excessive scar contraction and post‐burn scar contracture result from increased contraction forces generated by hypertrophic scar cells. This increased contractility appears to be mediated by increased endogenous presence of transforming growth factor‐β.