Abstract: Objective To explore the methods of proliferation and protection of dental pulp cells under hypoxia by observing the effect of erythropoietin(EPO) on the proliferation and differentiation of dental pulp cells under hypoxic conditions, in order to provide experimental reference for the protection of dental pulp cells under hypoxia.  
Methods Pulp cells were isolated and subcultured from healthy intact teeth of patients under 18 years of age requiring tooth extraction due to orthodontics or impaction by modified tissue enzyme digestion. The patients were divided into two groups under hypoxic conditions. In the experimental group, 10% FBS DMEM medium containing 20 U/mL EPO was used to culture dental pulp cells, while in the control group, DMEM with 10% FBS was used. The oxygen concentration of the incubator was set to 1%, and CCK-8 was employed to detect the effects of EPO on the proliferation of dental pulp cells at 24 h, 48 h, 72 h after culture. Alkaline phosphatase(ALP) activity was used to detect the effects of EPO on the mineralization of dental pulp cells. 
Results Dental pulp cells were cultured under hypoxic conditions. The results of CCK-8 showed that the CCK-8 values of the EPO group were higher than those of the control group at 24 h, 48 h, and 72 h, and the difference was statistically significant(P＜0.05). The results of ALP for detecting the differentiation ability of dental pulp cells showed that there was no significant difference in absorbance between the experimental group and the control group at 24 h, 48 h and 72 h. 
Conclusion EPO can protect dental pulp cells under hypoxia, promote their proliferation and anti-inflammatory effects, which, therefore, can be used as a protective drug for dental pulp cells under hypoxia in clinical practice. 

Key words: dental pulp necrosis, anoxia, erythropoietin