Acta Pharmacologica Sinica (2009) 30: 1245–1252; doi: 10.1038/aps.2009.122; published online 24 August 2009

Aim: To understand the effects of lithospermic acid (LA), a potent antioxidant from the water-soluble extract of Salvia miltiorrhiza, on the migration and proliferation of rat thoracic aorta vascular smooth muscle cells (VSMCs).

Methods: VSMC migration, proliferation, DNA synthesis and cell cycle progression were investigated by transwell migration analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, bromodeoxyuridine (BrdU) incorporation assay, and flow cytometric detection, respectively.  Intracellular reactive oxygen species (ROS) generation was detected using 2′,7′-dichlorofluorescin diacetate (DCFH-DA).  The expression of cyclin D1 protein and matrix metalloproteinase-9 (MMP-9) protein, as well as the phosphorylation state of ERK1/2, were determined using Western blots.  The activity of MMP-9 and the expression of MMP-9 mRNA were assessed by gelatin zymography analysis and RT-PCR, respectively.

Results: LA (25−100 μmol/L) inhibited both lipopolysaccharide (LPS)- and fetal bovine serum (FBS)-induced ROS generation and ERK1/2 phosphorylation.  By down-regulating the expression of cyclin D₁ and arresting cell cycle progression at the G₁ phase, LA inhibited both VSMC proliferation and DNA synthesis as induced by 5% FBS.  Furthermore, LA attenuated LPS-induced VSMC migration by inhibiting MMP-9 expression and its enzymatic activity.

Conclusion: LA is able to inhibit FBS-induced VSMC proliferation and LPS-induced VSMC migration, which suggests that LA may have therapeutic effects in the prevention of atherosclerosis, restenosis and neointimal hyperplasia.

Keywords: lithospermic acid; ERK1/2; matrix metalloproteinase-9; vascular smooth muscle cells; proliferation; migration