l-Caldesmon regulates proliferation and migration of vascular smooth muscle cells and inhibits neointimal formation after angioplasty

Objective - Light-type caldesmon (l-CaD) is a potent cytostatic and antiangiogenic protein that regulates cell growth and survival via modulation of the cell shape and cytoskeleton. The aim of this study is to explore the potential value of l-CaD for use as a cytostatic agent to inhibit neointimal formation after angioplasty by suppressing vascular smooth muscle cell (VSMC) growth and migration. Methods and Results - We tested the cytostatic function of l-CaD in cultured VSMCs using assays for apoptosis, cell proliferation, and migration, and evaluated the expression pattern of relevant signaling proteins ( focal adhesion kinase [FAK] and mitogen-activated protein kinases) in VSMCs. Transfection of adenoviral vector encoding l-CaD (Ad-l-CaD) resulted in progressive loss of actin stress fibers and cell retraction. Enzyme-linked immunosorbent assay demonstrated that Ad-l-CaD transfection increased the apoptosis rate by 75% and reduced BrdU uptake by 49%. Furthermore, transfection of Ad-l-CaD inhibited migration of VSMCs induced by platelet-derived growth factor-BB ( PDGF) by 36% ( P < 0.05). Immunoblotting analysis revealed that l-CaD overexpression reduced PDGF-induced phosphorylation of both FAK and extracellular signal regulated-kinase (ERK). In balloon-injured rat carotid arteries, Ad-l-CaD transfection inhibited neointimal formation by 37% (P < 0.05) without delaying re-endothelialization at 14 days. Conclusions - Overexpression of l-CaD suppressed cell growth and survival in VSMCs and inhibited neointimal formation after experimental angioplasty, partly by regulating the cytoskeletal tension-FAK-ERK axis.