THE EFFECTS OF EXTRACELLULAR MATRIX PROTEIN INSUFFICIENCY AND TREATMENT ON THE STIFFNESS OF ARTERIAL SMOOTH MUSCLE CELLS

摘要

Increased arterial stiffness is directly correlated with hypertension and cardiovascular disease. Stiffness of the conducting arteries is largely determined by the extracellular matrix (ECM) proteins in the wall, such as collagen and elastin, produced by the smooth muscle cells (SMCs) found in the medial layer. Elastin is deposited as soluble tropoelastin and is later crosslinked into elastin fibers. Newborn mice lacking the elastin protein (Eln-/-) have increased arterial wall stiffness and SMCs with altered proliferation, migration and morphology. Vessel elasticity is also mediated by other ECM proteins, such as fibulin-4. Elastic tissue, such as lung, skin, and arteries, from fibulin-4 deficient (Fbln4-/-) mice show no decrease in elastin content, but have reduced elasticity due to disrupted elastin fibers. Arteries from both elastin and fibulin-4 deficient mice have been previously studied, but the mechanical properties of their SMCs have not been investigated. Recent experiments comparing arterial SMCs from old and young animals suggest that mechanical properties of the SMCs themselves may contribute to changes in wall stiffness. Hence, we investigated the stiffness of isolated arterial SMCs from elastin and fibulin-4 deficient mice using atomic force microscopy (AFM). In addition, we studied the effects of two elastin treatments on the mechanical properties of SMCs from Eln+/+ and Eln-/- mice. Differences between the treatments may elucidate the importance of soluble versus crosslinked elastin on single cell stiffness.