COLLAGEN METABOLISM IN WOUND REPAIR AND KELOID

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The long-term objective of this project is to elucidate the cellular interactions and molecular mechanisms involved in the regulation of collagen metabolism during wound repair. The objective will be met first by determining if there is a selection of specialized subpopulations of fibroblasts after wounding, each with different potentials to produce collagen. These studies may explain why certain individuals are susceptible to excessive scar formation (keloid and hypertrophic scar), while others have decreased wound healing (hernia and malnutrition). Other studies focus specifically on fibroblasts and inflammatory cell interactions to determine how these interactions modulate the extent and quality of the fibrotic reponse. These studies will be pursued using the PVA implant in animals and humans to characterize inflammatory cell dynamics as they relate to connective tissue deposition during normal wound healing and following pharmacologic modulation. Further, the possibility that inflammatory cells produce collagen in the initial wound matrix will be explored further using light and electron immunohistochemistry, biochemical analysis, and molecular probe analysis. An in vitro model of fibroplasia will be used to reconstitute the wound environment to further determine the inflammatory, cellular and humoral participants in the ultimate fibrotic response. A low molecular weight, macrophage-derived chemotactic factor for fibroblasts which we have isolated will be purified further and characterized to determine the role in fibroblast chemotaxis. Recent technological advances in molecular biology now allow investigation into the genetic regulation of collagen metabolism during wound repair. Total mRNA will be isolated from dermal wound fibroblasts, from selected subsets of fibroblasts cultured under various environmental, nutritional and pharmacologic conditions, from the in vitro fibroplasia experiments, and from inflammatory cells in reconstituted blood clots. Using cell-free protein synthesizing systems and cDNA probe analysis, the level of transcriptional or translational control can be determined in those various systems. The net result of these multifacted studies of inflammation and wound repair will be a better understanding of the steps at which collagen metabolism is regulated and specific mechanisms which can be used to better control abnormal healing.