It is our intent to develop a cell culture model of tissue extracellular matrix injury. Cultured smooth muscle cells, with time, form a multilayered cell system containing cells embedded in an extracellular matrix in a "hills and valleys" format. If we liken this cell layer to the simplest of tissue specimens, we hypothesize that under normal circumstances minor injury to the extracellular matrix will provoke cellular responses leading to rapid, normal repair. When injury to the matrix is beyond normal repair, it is hypothesized that cellular responses occur which trigger additional damage, including those derived from infiltration of inflammatory cells, ultimately resulting in permanent loss of functional connective tissue (fibrotic or non-fibrotic). The focus of the proposal is to understand the relationships between matrix injury and cellular response and repair. Within the confines of the culture system, we will produce a biochemically defined matrix which, in turn, can be injured in a controlled and measureable manner and ultimately can be repaired by the cells embedded in the matrix. Preliminary studies are encouraging and suggest that this approach is feasible. Matrices can be developed in which the collagen, elastin, proteoglycan or fibronectin components may be labelled. In addition, the matrix content of collagen and elastin can be altered with various agents such as ascorbate and estradiol. These labelled defined matrices of varying composition are to be injured by treatment with leukocytic elastase and/or myeloperoxidase. The injury will be measured by a number of parameters including degradation or solubilization of labelled components and ultrastructural damage. The cellular response to the injury will be evaluated by monitoring the ability of the cells in culture to synthesize new matrix components and repair the damaged components, to proliferate and/or produce metabolites such as prostaglandins. In addition, attempts will be made to modulate these responses by the addition of agents such as prostaglandins and ascorbate. Findings from these studies should lead to new insights into the relationship between tissue injury and the pathogenesis of artery diseases such as atherosclerosis.