[Bax inhibitor-1 inhibits calcification of vascular smooth muscle cells in vitro].

Objective To investigate the effect of Bax inhibitor-1(BI-1)on calcification of vascular smooth muscle cells(VSMCs). Methods VSMCs were isolated from the thoracic aorta of SD rats.VSMCs or BI-1-overexpressing VSMCs(transfected with a BI-1-overexpressing plasmid) were cultured in normal medium or calcified medium containing β-glycerophosphate and calcium chloride, and the cell calcification was examined with Alizarin red staining.Enzyme-linked immunosorbent assay was used to determine the intracellular calcium content and alkaline phosphatase activity.The expression levels of Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP-2) and caspase-3 were detected with Western blotting. Results After 14 days of culture in the calcified medium, the VSMCs showed significantly reduced expression of BI-1 protein(P=0.001).BI-1 overexpression in the VSMCs caused a significant reduction of calcium level and alkaline phosphatase activities(P=0.0006) and lowered the expression levels of RUNX2 and BMP-2 (P=0.0001) in the cells.The VSMCs with induced calcification exhibited a significantly increased apoptosis rate, but BI-1 overexpression obviously inhibited VSMC apoptosis in the calcified medium (P=0.0003). Conclusion BI-1 may attenuate vascular calcification by inhibiting calcium deposition, osteogenic differentiation and apoptosis.