ABSTRACT
Connective tissue in the vascular system consists of vascular smooth muscle cells (VSMC) and the interstitial extracellular matrix (ECM). VSMC are located in the media of the vascular wall surrounded by their own basement membranes and embedded within an interstitial matrix consisting mainly of type I brillar collagen, the glycoprotein bronectin, tenascins, and dermatan and chondroitin sulfate proteoglycans (Raines 2000). Two major types of VSMC have been described, and their aberrant regulation is at the basis of atherosclerosis development: the contractile phenotype of VSMC is essential for hemodynamic stability and maintenance of the vascular tone, whereas the synthetic phenotype is capable of repairing the injured vessel wall by migrating, proliferating, and elaborating an appropriate ECM (reviewed in Alexander and Dzau 2000, Zingg and Azzi 2007). In addition to maintaining the vascular structure, connective tissue supports against mechanical stress generated by pulsatile blood ow, which results in hydrostatic pressure, cyclic tension, and wall shear stresses. Connective tissue cells respond to these stressors, adapt to them, and convert them into changes of the extracellular compartment (Chiquet et al. 2003).
