Abstract: Objective：To investigate the effects of liposomal formulation on simvastatin nano-liposomes (SMV-liposome) promoting the osteogenic differentiation of mice bone marrow stromal cells (BMSC) analyzed by the expressions of bone morphogenetic protein 2 (BMP-2) and alkaline phosphatase (ALP). Methods: Primary BMDC were cultured in vitro using adherence and culture of whole bone marrow method. SMV dosage was set as control group and had two different dosages in this group on the basis of the concentration of SMV. 1 μmol/L and 2 μmol/L SMV concentration were represented by SMV low dosage group (S1) and SMV high dosage group (S2), respectively. Similarly, SMV-liposome dosage was set as experimental group including two different dosages, 1 μmol/L SMV capsuled concentration as SMV-liposome low dosage group (SL1) and 2 μmol/L SMV capsuled concentration as SMV-liposome high dosage group (SL2). Besides, groups with no drug intervention in the experiments were set as blank. BMSC were treated with different concentrations of SMV and SMV-liposome for 48 h, the activity of ALP was measured using p-nitropheny-phosate method, and ALP expression in the BMSC cells was stained by BCIP/NBT alkaline phosphatase color development kit (BCIP/NBT Kit). Furthermore, BMP-2 expression in the BMSC was determined by Western Blot. Results: MTT assay showed, after incubated with different concentrations of SMV and SMV-liposome, the cell viabilities of BMSC were all above 85% and had no significant difference in the groups. Compared with the same dosage of SMV in these groups, control group and experimental group had significantly elevated the specific activity of ALP, the staining of BCIP/NBTKit as well as the protein expression of BMP-2. Besides, the data showed dosedependent elevation in the control group and experimental group, namely the high dose group had better results than the low dose group. Conclusion: Nano-liposomal formulation significantly enhanced SMV effects on the osteogenetic differentiation of BMSC.

Key words: Simvastatin, Mesenchymal stromal cells, Liposomes, Bone morphogenetic proteins, Alkaline phosphatase