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-beta or anti-transforming growth factor-beta antibody examined the role of this cytokine on lattice contraction. Transforming growth factor-beta 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-beta increased lattice contraction by normal skin fibroblasts but had little effect on hypertrophic scar cell-populated lattices. The addition of anti-transforming growth factor-beta antibody decreased lattice contraction by both cell types. Transforming growth factor-beta 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-beta.