BACKGROUND:Osteoporosis caused by chemotherapy has become one of the serious side effects that impact the skeletal system. Icarin shows a strong anti-osteoporosis activity, which can have protective effect on osteoporosis induced by chemotherapy. OBJECTIVE: To study the protective effect and mechanism of icarin against cyclophosphamide-induced obstacle of mouse bone marrow mesenchymal stem cels differentiating into osteoblasts. METHODS:MTT assay and alkaline phosphatase (ALP) staining were used to determine the optimal protective concentration of icarin against cyclophosphamide-induced obstacle of mouse bone marrow mesenchymal stem cels differentiating into osteoblasts. mRNA expressions of osteoblast-specific transcription factors, OC, ALP, Runx2, and Wnt/β-catenin signaling pathway target genes, β-catenin, C-Myc, cyclin D1, were determined using RT-PCR method at different time after intervention with the optimal concentration of icarin. Expressions of Runx2, β-catenin, c-Myc, cyclin D1 regulated by the optimal concentration of icarin were detected using western blot assay at the protein level. RESULTS AND CONCLUSION:Cel viability and ALP activity decreased significantly in the cyclophosphamide group compared with the control group, but there was no significant difference in cel viability between icarin group and cyclophosphamide group. Icarin at 100 μmol/L showed the best protective effect against cyclophosphamide-induced obstacle of osteogenic differentiation of bone marrow mesenhymal stem cels. Compared with the control group, cyclophosphamide chemotherapy reduced the expressions of ALP, OC, Runx2 at mRNA level and Runx2 at protein level, weakened the expressions ofβ-catenin, cyclin D1 at mRNA level and active β-catenin, Cyclin D1, c-myc at protein level, and increased the expression of DKK1. Compared with the cyclophosphamide group, 100 μmol/L icarin increased the expression of osteoblast-specific transcription factors and Wnt/β-catenin signaling pathway genes at mRNA and protein levels, and reduced the expression of DKK1 protein. These results show that cyclophosphamide can lead to osteogenic differentiation disorder of mouse bone marrow mesenchymal stem cels, and in contrast, icarin shows a protective effect and its optimal intervention concentration is 100 μmol/L. Additionaly, the protective roleof icarin is probably related to activation of Wnt/β-catenin signal pathway.