Culture of human smooth muscle cells.

The wall of a human artery consists of three distinct tunics. The tunica intima is lined by a layer of endothelial cells facing the lumen. Smooth muscle cells (SMCs) are the predominant cell type in the tunica media of arteries. They are surrounded by a basal lamina containing collagen IV, proteoglycans, glycosaminoglycans, glycoproteins, and extracellular matrix (ECM) molecules: collagens type 1, III, V, and VI, and elastin. The external tunica adventitia consists primarily of collagen fibers, elastic tissue, and fibroblasts. Because smooth muscle cells play a dominant role in the development of intimal hyperplasia during atherosclerosis, these cells have been studied extensively in vitro.