Objective To observe the growth and osteogenic property of cultured dog bone marrow stem cells （BMSCs） by investigating the effects of astragalus polysaccharides（APS） on the proliferation and ultrastructure of BMSCs into osteoblasts in vitro. Methods BMSCs osteogenic property was detected by improved Wright - Giemsa, Gomori and alizarin dyeing method. The proliferation and differentiation of the induced BMSCs with APS in different concentration and time were detected by MTT assay and the morphologic change of the induced BMSCs was observed by transmission electron microscope（TEM）. Results BMSCs osteogenic property was detected with Wright - Giemsa deep- bluing, Gomori method blacking and with more mineral nodules alizarin dyeing method carmining. APS with concentration of 0.005 mg/mL can promote the proliferation of the induced BMSCs in short - term culture（1th, 3th day） and 50 mg/mL can decrease the effect through long- term culture（5th day）. Observed by TEM（5th day）, the number of mitochondria, rough endoplasmic reticulum increased and the extracellular matrix was excreted more in the induced BMSCs by APS with concentration of 0.005 mg/mL. However, not only the number of mitochondria, rough endoplasmic reticulum reduced but also the structure was swollen, degenerative, membrance damaged in the induced BMSCs by APS with concentration of 50 mg/mL. Conclusion APS with lower concentration in short - term culture may promote BMSCs proliferation and differentiation.
