ECM Remodeling in Excessive Fibroplasia

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The long term goal of the research is to elucidate the cellular and molecular basis of excess scar formation during wound repair. Keloids are tumor-like skin scars that affect 10 to 20% of people of African decent, Asians, and Hispanics without appropriate treatments. During the past funding period, we used 14 freshly isolated and low passages (<3) strains of normal and keloid fibroblasts from human patients and provided new evidence that (PAI-1) overexpression and elevated collagen accumulation are intrinsic features of keloid fibroblasts. We also provided new and different evidence of a causal relationship between PAI-1 expression and collagen accumulation: adenoviral overexpression and siRNA and shRNAmir suppression demonstrate that PAI-1 produces elevated collagen accumulation in normal and keloid fibroblasts, respectively. Finally, by testing protease-inhibitory and vitronectin-binding mutants of PAI-1 for their capacity to induce collagen accumulation, we found that the latter was equipotent with wild-type PAI-1 and the former was only ~50% effective. Thus, PAI-1 utilizes protease inhibition as well as another of its functions to control collagen accumulation (Tuan et al., 2008, Am J Pathol). The goals of the renewal application are 1) to advance a therapeutic strategy that targets plasminogen activator inhibitor-1 (PAI-1) to control keloid collagen accumulation and prevent or treat keloid formation; 2) to further define and expand the mechanisms utilized by PAI-1 to regulate collagen accumulation in keloid fibroblasts.