Effect of thrombin on brain microvascular endothelial cell in vitro

Objective:To explore the mechanism of the opening of blood brain barrier induced by thrombin (TM). Methods:Brain microvascular endothelial cells were cultured in vitro . After thrombin or thrombin+cathepsin G was added into the medium,the changes in the morphology of endothelial cell were dynmatically observed with phase contrast light microscopy and the expression of matrix metalloproteinase 2 (MMP 2) was measured with immuohistochemical method. Results:Cells began to contract after thrombin incubation, resulting in increased intercellular spaces and reduced cell areas. Cell contraction was time dependent. By 12 h after thrombin incubation , the area of cell was only 20 percent of that before treatment. The expression of MMP 2 was markedly increased compared with control group( P 0.01).After thrombin+cathepsin G incubation, the morphology and MMP 2 expression of cells had no significant difference compared with control group( P 0.05). Conclusion: Thrombin might induce endothelial cell contraction and promote MMP 2 expression by activating protease activated receptor 1 (PAR 1),and this may be the mechanism of BBB opening induced by thrombin. \[