Abstract: Objective To investigate the effect of Rat bone marrow mesenchymal stem cells (MSCs) on apoptosis of hepatic stellate cells (HSCs) by co-cultured, and explore the underlying mechanism of MSCs on the HSCs. Methods MSCs were isolated and cultured from bone marrow in rats . HSCs and fiberoblast cells were recoveried and activated morphologically，a-SMA expression in HSCs was evaluated immuno-histochemically. The co-culture of MSCs with HSCs were performed by using a 6-well Transwell membranes (24mm diameter, 0.4 μm pore size).The HSCs were seeded in the lower chamber with MSCs and fiberoblast cells (2×105cells /ml) were seeded onto the Transwell membrane of the inner chamber.Cultures were maintained in HSCs in medium for 24h、48h and 72h. Three groups were divided: ①HSCs control group②fiberoblast control group③MSCs group. At the different pointed time, the inhibitory rate of HSCs proliferation with MSCs co-culture were tested by the method of WST-8, and the rate of apoptosis of HSCs were detected by Annexin-V-FITC/PI and DNA Ladder, and the HSCs in co-culture system were collected and the mRNA expressions of Caspase-3,Bax in HSCs were detected by RT- PCR . The protein expressions of Caspase-3,Bax in HSCs were evaluated by Western blot. Results With the co-culture time lasting, MSCs group showed the strip of DNA Ladder, the inhibitory rate of HSCs ,the rate of apoptosis of HSCs and the mRNA expression of Caspase-3,Bax and Caspase-3,Bax protein in MSCs group were significantly increased at time 24h, which were significant higher than control groups(P<0.01）, and the same effection was taken place at the following times. Conclusions MSCs could induce apoptosis of HSCs in vitro by up-regulating the expression levels of Caspase-3 and Bax, and thus play important role in the antifibrosis

Key words: bone marrow mesenchymal stem cells, hepatic stellate cells, apoptosis, Caspase-3, Bax