The effect of electromagnetic fields on survival and proliferation rate of dental pulp stem cells

Abstract

Introduction: Extremely low-frequency electromagnetic fields (ELF-EMF) can effect on biological systems and alters some cell functions like proliferation rate. Dental pulp tissue has been known as a source of multipotent stromal stem cells (MSCs), which can be obtained by a less invasive method and in large amounts compared with bone marrow derived stem cells (BMSCs). This study aimed to consider the effect of ELF-EMF on survival and proliferation rate of human dental pulp -derived stem cells (hDPSCs).

Methods and Materials: ELF-EMF was generated by a system including autotransformer, multi-meter, solenoid coils, teslameter and its probe. The effect of ELF-EMF with 0.5 and 1 mT and 50 Hz was evaluated on proliferation rate of dental pulp stem cell for 20 and 40 min/day for 7 days. The exposed cells were in six groups with the different EMF doses. Group 1: 1 mT for 40 min/day, group 2: 1 mT for 20 min/day, group 3: 0.5 mT for 40 min/day and group 4: 0.5 mT for 20 min/day. The control groups were also placed in the turned off solenoid coils for 20 and 40 min/day. Conditions for exposure and control groups were the same. In all experiments, the plates were located at the center of solenoid where the magnetic field was most uniform. MTT 3- [4,5-dimethylthiazol-2-yl] -2,5-diphenyl-tetrazolium was used to determine cell growth and DAPI40,6-diamidino-2-phenylindole test for cell survival. Statistical analyses were carried out using Prism software version 6.0. Data are represented as means ± SD. The statistical significance was determined using the One-Way ANOVA followed by a post hoc multiple comparisons Tukey test. P value less than 0.05 was considered statistically significant.

Results: Based on MTT assay; ELF-EMF has maximum effect with intensity of 1mT for 20 min/day on proliferation of hDPSCs. The survival and proliferation rate in all exposure groups were significantly higher than control group. Based on the data obtained from genotoxicity assay, The number of micronuclei in the group exposed to 1mT for 20 min/day was higher than that in all treatments and control groups (P<0.05). The differences between group of 0/5 mT with 40min/day exposure with control was significant (P=0/032) but differences between the group of 1 mT with 40min/day with control was not significant (P=0/885). Conclusions: It can be concluded that 0.5 and 1 mT ELF-EMF could be enhances survival and proliferation rates of hDPSCs regarding the duration of exposure.