Effect of Hirudin on Calcification of Rat Vascular Smooth Muscle Cells Induced by High Phosphorus

OBJECTIVE To explore the effect and mechanism of hirudin on calcification of vascular smooth muscle cells (VSMCs) induced by high phosphorus. METHODS Rat VSMCs cultured in vitro were induced by β-glycerophosphoric acid to establish calcification model, and different concentrations of hirudin were added to intervene. The experiment set five groups: control group, calcification group, low concentration hirudin group, medium concentration hirudin group and high concentration hirudin group. The cellular calcification was detected by alizarin red S staining and intracellular calcium content. The activity of alkaline phosphatase(ALP) and the mRNA and protein expression of α-SMA, RUNX2, BMP2 which were assayed by qRT-PCR and Western blotting to detect the transdifferentiation of cells in each group. RESULTS Compared with the control group, alizarin red S staining showed obvious orange calcium nodules in high phosphorus-induced calcification group, the detection of calcium content showed that the calcium content in cells increased significantly(P<0.01), intracellular ALP activity increased(P<0.01), mRNA and protein expression of α-SMA decreased(P<0.01), mRNA and protein expression of RUNX2 and BMP2 increased(P<0.01). Compared with calcification group, the number of orange-red calcium nodules stained by alizarin red S in hirudin group decreased in a concentration-dependent manner, the intracellular calcium content and ALP activity decreased in a concentration-dependent manner(P<0.05 or P<0.01), the mRNA and protein expression of α-SMA increased in a concentration-dependent manner(P<0.05 or P<0.01), the mRNA and protein expression of RUNX2 and BMP2 decreased significantly in a concentration-dependent manner(P<0.05 or P<0.01). CONCLUSION Hirudin attenuates the calcification of VSMCs by inhibiting the transdifferentiation of VSMCs induced by high phosphorus. The mechanism may be related to the up-regulation of α-SMA expression and down-regulation of ALP activity, RUNX2 and BMP2 expression.