Abstract 237: The Inhibitory Effect on Vascular Smooth Muscle Cell Hyperplasia in Artificial Atherosclerotic Mouse Model via miR-155 Induced NoxA1 Down Regulation

Abstract

Objective: To investigate the protective efficacy of miR-155 on down regulating NoxA1 gene expression, resulting in an inhibitory effect of vascular smooth muscle cell (VSMC) over proliferation and thus alleviating the progression of coronary artery atherosclerosis in mouse disease model. Methods: Carotid artery of C57BL6 mouse was used for VSMC primary culture. The isolated VSMC was transfected with recombinant Pad2YFG adenovirus fluorescent vector with miR-155 fragment (mimic or mutant). Fluorescence microscope was applied to observe the transfection rate of miR-155 into VSMC. Artificial artery-injured mouse model fed with high-fat diet was established as host to accept VSMC transplantation via tail vein injection for 3 consecutive days. Aortic and carotid arteries were extracted at week 6. Distribution of miR-155 was quantified; protein and RNA were extracted to detect NoxA1 and NADPH expression in vehicle control, miR-155 mimic group, and the inhibitor group. Immunohistochemistry was performed in arteries section to compare the thickness of neointima and assess the severity of AS of each group. Results: The miR-155 distribution was observed varied at week 6 in control, miR-155 mimic and inhibitor groups. The NoxA1 protein expression in VSMC was decreased in mimic group at week 6 vs control and inhibitor groups (p<0.05); no significant difference of NADPH expression was observed in all groups. The NoxA1 and NADPH gene expression in VSMC were both found reduced compared with those of control group at week 6 (p<0.05). Immunohistochemistry of artery frozen sections figured out that the thickness of neointima of carotid artery in miR-155 mimic group was significantly lower vs control and inhibitor groups (p<0.01) at week 6. Conclusion: miR-155 transfection into VSMC seems to have reversed regulatory effect on NoxA1 expression resulting in amelioration of atherosclerotic lesion in artificial AS mouse model. A therapeutic strategy based on the functional role of miR-155 in VSMC over proliferation-based atherosclerosis would need to complementarily-synthesize miRNAs, which is a promising therapeutic tool due to the enhanced stability and sustained effects after intravenous injection in the arterial wall.