ECM REMODELING IN EXCESSIVE FIBROPLASIA

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To elucidate the cellular and molecular basis of excess scar formation during wound repair. The present application will focus on the cellular and molecular differences between normal scar and keloid fibroblasts with a special emphasis on the altered regulation of the PAI/uPA system in keloid fibroblasts. Information obtained from this study may lead to development of methods for prevention and treatment of excess scar formation during wound repair. The investigators will approach the long term goal by elucidating the pathologic mechanisms of excess scar formation using an in vitro fibroplasia model as an environment for perturbing matrix remodeling directed by normal scar and fibrotic fibroblasts. The investigators have demonstrated that keloid fibroblasts exhibit changes in fibrin matrix remodeling by expressing elevated levels of plasminogen activator inhibitor-1 (PAI-1) and basal and transforming growth factor-beta (TGF-b) stimulated-levels of collagen. These changes may be mediated at the TGF-b receptor level, since a difference in the TGF-b type I receptor profile in keloid fibroblasts was identified. The investigators hypothesize a) that increased expression of PAI-1 in keloid fibroblasts leads directly to defective fibrin degradation and persistent fibroplasia in keloids, and b) that increased responsiveness to TGF-b, mediated by an altered profile of receptors, induces this elevated PAI-1 expression in keloid cells. The investigators will test these hypotheses with four specific aims: Specific Aim 1: To characterize a matrix remodeling phenotype for normal scar and keloid fibroblasts. Specific Aim II. To test for the presence of a cause and effect relationship between uPA/PAI-1 and acute changes in fibrin degradation by manipulating uPA/PAI phenotypic expression in normal scar and keloid fibroblasts using retroviral transduction of PAI-1/antisense PAI-1 into these cells. Specific Aim III. To determine if a direct cause and effect relationship exists between a specifically altered uPA/PAI-1 phenotype and the nature of the remodeled ECM that develops over time. Specific Aim IV. To characterize TGF-b receptors from keloid fibroblasts and determine whether ligand binding or receptor signaling are responsible for the increased synthesis of PAI-1 and collagen by keloid fibroblasts in this model.