Anti-fibrotic Effects and Mechanism of Shengmai Injection(生脉注射液)on Human Hepatic Stellate Cells LX-2

Objective: To investigate the effects of Shengmai Injection(生脉注射液, SMI) on the proliferation, apoptosis and N-myc downstream-regulated gene 2(NDRG2, a tumour suppressor gene) expression in varying densities of human hepatic stellate cells LX-2. Methods: LX-2 cells were cultured in vitro. Then, cells were plated in 96-well plates at an approximate density of 2.5×10～4 cells/mL and cultured for 48, 72, 96 or 120 h followed by the application of different concentrations of SMI(0.6, 1.2, 2.4, 4.8 or 6 μL/mL). Cell proliferation was measured after an additional 24 or 48 h using the 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. The effects of SMI on different cell growth states(cultured for 48, 72, 96, or 120 h) were observed by light microscopy at 24 h after treatment. When the cells reached 80% confluence, apoptosis was detected by flow cytometry after 24 h. Lastly, LX-2 cells were treated with different concentrations of SMI and extracted with protein lysis buffer. The levels of NDRG2 were measured by Western blot. Results: When the LX-2 cells grew for 48, 72, 96 and 120 h, 4.8 and 6 μL/m L of SMI significantly inhibited cell proliferation at 24 and 48 h after treatment(P<0.05). And 2.4 μL/mL of SMI also inhibited cell proliferation at 24 h after treatment when cell growth for 48 h(P<0.05) and at 48 h after treatment when cell growth for 72, 96 and 120 h(P<0.05). The NDRG2 expression level in the LX-2 cell was significantly increased when treated with SMI at concentrations of 1.2, 2.4, 4.8 or 6 μL/mL(P<0.05). Conclusions: The inhibitory effects of SMI on the proliferation of LX-2 cells were related to not only concentration dependent but also cell density. In addition, SMI(2.4, 4.8 and 6 μL/mL) could accelerate apoptosis in LX-2 cells, and the mechanism might be associated with NDRG2 over-expression.