Cell biology of valvular interstitial cells.

To review the cell biology of the interstitial cells of heart valves. While studying the function of interstitial cells of heart valves, the authors observed that interstitial cells from porcine mitral valve have mixed phenotypic expression. English-language literature from 1985-95 that discussed the cell biology of heart valve interstitial cells, including their structural and functional characteristics. Morphologically, heart valve interstitial cells have characteristics of both fibroblasts and smooth muscle cells. It is not clear, however, whether these cells represent a single (myofibroblast) cell type or whether there are two populations of cells within the valve. This review summarizes reports of the structural and functional characteristics of heart valve interstitial cells including ultrastructure, cell junctions, smooth muscle cell markers, cell growth, role in wound repair and contractility. Vascular interstitial cells play an important role in both normal and diseased valves. Our understanding of the heterogeneity of valvular interstitial cells is incomplete; however, this heterogeneity allows for multiple functions to be carried out including cell-cell communication, matrix secretion, wound repair and contractility. Future studies are needed to focus on the regulation of cellular heterogeneity as it relates to valve structure and function in health and disease.