Molecular basis of the effects of mechanical stretch on vascular smooth muscle cells.

The pulsatile nature of blood pressure and flow creates hemodynamic stimuli in the forms of cyclic stretch and shear stress, which exert continuous influences on the constituents of the blood vessel wall. Vascular smooth muscle cells (VSMCs) use multiple sensing mechanisms to detect the mechanical stimulus resulting from pulsatile stretch and transduce it into intracellular signals that lead to modulations of gene expression and cellular functions, e.g., proliferation, apoptosis, migration, and remodeling. The cytoskeleton provides a structural framework for the VSMC to transmit mechanical forces between its luminal, abluminal, and junctional surfaces, as well as its interior, including the focal adhesion sites, the cytoplasm, and the nucleus. VSMCs also respond differently to the surrounding structural environment, e.g., two-dimensional versus three-dimensional matrix. In vitro studies have been conducted on cultured VSMCs on deformable substrates to elucidate the molecular mechanisms by which the cells convert mechanical inputs into biochemical events, eventually leading to functional responses. The knowledge gained from research on mechanotransduction in vitro, in conjunction with verifications under in vivo conditions, will advance our understanding of the physiological and pathological processes involved in vascular remodeling and adaptation in health and disease.