[Mechanism of bone marrow-derived mesenchymal stem cell-promoted apoptosis of hepatic stellate cells].

OBJECTIVE: To explore the role of the Rho pathway in the hepatocyte growth factor (HGF) paracrine signal-mediated bone marrow-derived mesenchymal stem cell (BMSC) promotion of apoptosis of hepatic stellate cells (HSCs). METHODS: A BMSC-HSC co-culture system was established using plates with transwell inserts. Dynamic changes in response to pretreatment with the c-met blocker PHA665752 and the Rho pathway inhibitor Y-27632 were observed under an inverted phase contrast microscope at 24, 48 and 72 h of culture. Optimal intervention concentrations of Y-27632 and PHA665752 were determined by MTT assay. Expression of alpha-smooth muscle actin in HSCs was evaluated by immunohistochemistry, and the apoptosis rate of HSCs was measured by Annexin-V-FITC/propidium iodide. RhoA protein and mRNA levels were measured by western blot and quantitative real-time PCR respectively. Concentrations of HGF and hepatocyte growth factor activator (HGFA) were quantified by enzyme-linked immunosorbent assay. Between-group differences were evaluated by one-way ANOVA with P less than 0.05 indicating significance. RESULTS: The apoptosis rates of HSCs gradually and steadily increased in a time-dependent manner. The apoptosis rate of the PHA665752 pretreated group was lowest and that of the Y-27632 pretreated group was highest, with the most robust difference occurring at the 72 h time point (P less than 0.05). The mRNA and protein expression levels of RhoA decreased in a time-dependent manner in the Y-27632 pretreated group (all time points, P less than 0.05) but the expression levels increased in a time-dependent manner in the PHA665752 pretreated group (all time points, P less than 0.05). For both the PHA665752 and the Y-27632 pretreated groups, the concentration of HGF decreased in a time-dependent manner, but the concentrations in both remained significantly higher than that in the control group at all time points examined (P less than 0.05). The concentration of HGFA increased in a time-dependent manner, and the PHA665752 pretreated group showed significantly higher levels than any of the other groups at all time points examined (P less than 0.01). CONCLUSION: BMSC promotes HSC apoptosis in a co-culture system by activating HGF and down-regulating the RhoA signaling pathway.