目的  探讨低氧化应激下肿瘤坏死因子α(TNF-α)过表达对牙髓干细胞(DPSCs)生物学性能的影响。   方法  实验分组为常氧DPSCs组、常氧空载转染组、常氧TNF-α过表达组、DPSCs 3% O2组、空载DPSCs 3% O2组、TNF-α过表达3% O2组。牙髓干细胞复苏并培养，然后将慢病毒TNF-α 转染细胞置于37 ℃、CO2培养箱培养， ELISA法检测各组细胞TNF-α的表达水平，RT-PCR检测TNF-α过表达氧化应激作用下的表达，Real-time PCR、Western blotting检测氧化应激作用下人DPSCs碱性磷酸酶（ALP）、牙本质涎磷蛋白（DSPP）表达和MTT检测各组细胞TNF-α转染后细胞增殖情况。   结果  Lentivirus-TNF-α转染细胞10 h 后，即可在倒置荧光显微镜下观察到绿色荧光信号，TNF-α过表达可以使低氧环境中牙髓干细胞增殖能力增强，且低氧的微环境可以增加TNF-α的表达，使DPSCs可以进一步的表达TNF-α，而且TNF-α过表达3% O2 时，Western blotting和Real-time PCR检测都表明DPSCs中ALP、DSPP表达差异具有显著性（P<0.05）。   结论  低氧微环境中DPSCs过表达TNF-α可以同时提高增殖效率和较高的分化效果。 

Objective  To investigate the effect of tumor necrosis factor-α(TNF-α) on biological properties of dental pulp stem cells (DPSCs) in low-oxidation stress.    Methods  The experimental groups were as follows: normox, normox control plasmid, normox-TNF-α, 3% O2, control plasmid-3% O2、TNF-α-3% O2.DPSCs were resuscitated and cultured firstly, then lentivirus TNF-α transfected cells were cultured in a CO2 incubator at 37 ℃. The expression of TNF-α  was detected by ELISA in each group, and the expression of TNF-α under oxidative stress was detected by RT-PCR,the expressions of alkaline phosphatase(ALP) and dentin sialophosphoprotein(DSPP) were detected by Real-time PCR and Western blotting,the proliferation of DPSCs cells transfected with TNF-α was detected by flow cytometry and MTT.    Results  After lentivirus-TNF-α transfected cells for 10 hours, the green fluorescence signal could be observed under inverted fluorescence microscope, TNF-α overexpression could enhance the proliferation of DSPP in hypoxic environment,and hypoxia microenvironment can greatly increase the expression of TNF-α, Western blotting and Real-time PCR showed that there were significant differences in the expression of ALP and DSPP in DPSCs（P<0.05）.    Conclusion  TNF-α overexpression can improve the proliferation efficiency and differentiation efficiency of DPSCs in hypoxic microenvironment.