Abstract: Objective　 To discuss the biological effect of tumor necrosis factor-α on the proliferation and osteogenic/dentinogenic differentiation ability of stem cells from rat apical papilla. Method: Root nipple tissue in rat was separated and SCAP was extracted by combining enzyme digestion method with tissue block method. The cells were identified by fluorescence immunoassay. The cells were divided into experimental groups (TNF-α 5, 10, 15, 20, 30, 40, 50 ng/mL) and control group (TNF-α 0 ng/mL).The proliferation of SCAP was evaluated by CCK-8 method, and alkaline phosphatase activity, alizarin red staining and quantitative real-time PCR were applied to evaluate the effect of tumor necrosis factor-α on the ability of osteogenic/dentinogenic differentiation of SCAP. Result: SCAP was consistent with the characteristics of mesenchymal stem cells and had the ability of multi-directional differentiation. The proliferation of SCAP results showed that each concentration group could promote the proliferation of SCAP, the difference was statistically significant(P<0.05).The ALP activity showed that each concentration of TNF-α could significantly reduce the activity of ALP, and the difference was statistically significant(P<0.05). The alizarin red staining showed that with the increase of the concentration of TNF-α, the staining gradually became lighter, the red nodule gradually became smaller, and the number of the formation decreased gradually. The quantitative real-time PCR showed that the expressions of OC, DMP-1 in the experimental groups were significantly lower than the control group in 3 days(P<0.05), the expression of DSPP was significantly lower (P>0.05), while the expression of BSP was slightly higher(P<0.05). In 7days, the expressions of OC, DSPP in the experimental groups were significantly lower than the control group(P>0.05), the expression of DMP-1 was significantly lower(P<0.05), while the expression of BSP was slightly higher (P<0.05). In 14 days, the expressions of OC, DMP-1 and BSP in the experimental groups were significantly lower than the control group(P<0.05), while the expression of DSPP was slightly higher(P<0.05). Conclusion: TNF-α can promote the proliferation and inhibit the osteogenic/dentinogenic differentiation of SCAP in different degrees.

Key words: stem cells from rat apical papilla, tumor necrosis factor-α, osteogenic/dentinogenic differentiation