Use of 0.4‐Tesla static magnetic field to promote reparative dentine formation of dental pulp stem cells through activation of p38 MAPK signalling pathway.

Aim: To investigate whether static magnetic fields (SMFs) have a positive effect on the migration and dentinogenesis of dental pulp stem cells (DPSCs) to promote reparative dentine formation. Methodology: In vitro scratch assays and a traumatic pulp exposure model were performed to evaluate the effect of 0.4‐Tesla (T) SMF on DPSC migration. The cytoskeletons of the DPSCs were identified by fluorescence immunostaining and compared with those of a sham‐exposed group. Dentinogenic evaluation was performed by analysing the expressions of DMP‐1 and DSPP marker genes using a quantitative real‐time polymerase chain reaction (qRT‐PCR) process. Furthermore, the formation of calcified deposits was examined by staining the dentinogenic DPSCs with Alizarin Red S dye. Finally, the role played by the p38 MAPK signalling pathway in the migration and dentinogenesis of DPSCs under 0.4‐T SMF was investigated by incorporating p38 inhibitor (SB203580) into the in vitro DPSC experiments. The Student's t‐test and the Kruskal–Wallis test followed by Dunn's post hoc test with a significance level of P < 0.05 were used for statistical analysis. Results: The scratch assay results revealed that the application of 0.4‐T SMF enhanced DPSCs migration towards the scratch wound (P < 0.05). The cytoskeletons of the SMF‐treated DPSCs were found to be aligned perpendicular to the scratch wound. After 20 days of culture, the SMF‐treated group had a greater number of out‐grown cells than the sham‐exposed group (nonmagnetized control). For the SMF‐treated group, the DMP‐1 (P < 0.05) and DSPP genes (P < 0.05), analysed by qRT‐PCR, exhibited a higher expression. The distribution of calcified nodules was also found to be denser in the SMF‐treated group when stained with Alizarin Red S dye (P < 0.05). Given the incorporation of p38 inhibitor SB203580 into the DPSCs, cell migration and dentinogenesis were suppressed. No difference was found between the SMF‐treated and sham‐exposed cells (P > 0.05). Conclusion: 0.4‐T SMF enhanced DPSC migration and dentinogenesis through the activation of the p38 MAPK‐related pathway. [ABSTRACT FROM AUTHOR]