siRNA silencing reveals role of vascular cell adhesion molecule-1 in vascular smooth muscle cell migration.

Vascular cell adhesion molecule-1 (VCAM-1) is an adhesion molecule expressed by endothelial cells for recruitment of leukocytes during inflammation. It is also abundantly expressed by smooth muscle cells in atherosclerotic lesions and in injured arteries. In this study, we examined the role of VCAM-1 in smooth muscle cell migration. Smooth muscle cells were isolated from the aorta of C57BL/6 mice and transfected with short interfering RNAs (siRNAs) targeting VCAM-1. Inhibition on VCAM-1 expression by siRNAs was assessed by Western blot analysis, RT-PCR and by measuring soluble VCAM-1 concentrations in the incubation medium. One siRNA that showed greater suppression on VCAM-1 expression was used for migration assay. A single scratch wound was made on 70% confluent cells and cells migrated from wounded monolayer were counted 24 and 48h after injury. Treatment with VCAM-1 siRNA resulted in a significant reduction in the number of migrated cells. This siRNA also exhibited a minor effect on smooth muscle cell proliferation. Thus, our findings indicate that VCAM-1 is necessary for the migration of smooth muscle cells and interfering VCAM-1 expression could be an effective approach to prevention and treatment of atherosclerosis and restenosis.