Objective:To observe the effect of olfactory ensheathing cells (OECs) conditioned medium on NF,synapsin and synaptophysin expression in PC12 cells,and investigate the mechanism of olfactory ensheathing cell conditioned medium to promote growth of nerve cell differentiation. Methods:Primarily cultured OECs were prepared and purified,and the purified cell conditioned medium was collected into the olfactory ensheathing cell culture medium,then used to culture PC12 cells in 24 h,48 h,72 h. In vitro the morphological changes of the PC12 cells were observed under a phase contrast microscope;The expression and distribution of NF was determined by immunofluorescence methed;The relative content of NF,synapsin and synaptophysin proteins was detected by Western blot. Results:PC12 cells have long processes cultured in OECCM,and with the extension of the culture time,the cell morphology resembles neurons. Immunofluorescence staining showed the distribution of NF initially in the perinuclear. After the effects of OECCM the distribution of NF,increased and the ratio to β-tubulin was significantly high(P < 0.05).Western blotting showed the expression level of NF synapsin,and synaptophysin was significantly higher in OECCM group than in control group(P < 0.05). Conclusion:Olfactory ensheathing cells can secrete a number of cytokines to promote PC12 cell differentiation. These cytokines can promote the assembly of NF skeleton in PC12 cells,and induce neuronal function protein expression. So the cells can differentiate to the neurons in the structure and function.