Isolated smooth muscle cells in culture do not immediately start dividing, even in a medium containing all nutrients required. Before entering the cell cycle, the cells first accomodate their phenotype to their new environment. They lose their contractile properties and modulate to a proliferative and synthetic phenotype, characterised by decreased contractile protein and M3 receptor expression, but enhanced expression of PKC and synthetic organelles [1;2]. This process of phenotypic modulation has been postulated to occur in vivo during periods of airway inflammation, in view of the increased airway smooth mucle (ASM) mass seen asthmatics which is partly due to an increase in cell number [3]. A central role for phenotypic modulation in smooth muscle growth is also acknowledged in vascular remodeling. In atherosclerotic lesions, neointima formation is accompanied by modulation of smooth muscle cell phenotype to favour conditions of growth and extracellular matrix deposition. ... Zie: Chapter 11
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