Non-thermal effects of radiofrequency electromagnetic fields exposure on neural stem cells

In literature there are many evidences suggesting the ability of high frequency (3 MHz - 300 GHz) electromagnetic fields to influence biological systems, interfering with some regulation and control processes. However, up to date, the action mechanisms are not well understood. It should be better clarified their connection with the characteristics of the impinging electromagnetic field, that is Specific Absorption Rate (SAR), exposure time (chronic or acute), frequency and type of modulation [1-3]. In these contribution, we present the first results assessing the non-thermal effects induced by exposure on primary Olfactory Ensheathing Cells (OECs) to continuous and amplitude modulated 900 MHz EMF, in far field condition and at different time expositions (10, 15, 20 minutes). OECs are typical glial cells showing characteristics of stem cells. They express several growth factors and are able to promote axonal regeneration and functional restoration in the injured sites of Central Nervous System. Furthermore, it is known that a reduced functionality of olfactory system represents an early sign of neurodegeneration. The OECs were isolated from olfactory bulb of 2-day old mouse pups [4] and divided into three groups (control, sham and tests). The control samples were kept in the incubator at 37 ° C in an environment of humidified air and CO2 (95% -5%). Sham and tests were placed in a thermostatic bath, appropriately realized, at 37°C for the duration of the exposure. As sham it is intended a sample treated as test samples but not exposed to EMFs. The tests were exposed in far-field conditions to EMFs at 900 MHz continuous (CW 900 MHZ) and amplitude modulated at 50 Hz (AM 900 MHz), electromagnetic wave amplitude ~ 7 V/m in both exposure modes, and at three exposure times: 10, 15 and 20 minutes. The expression of the marker proteins of the OECs (S-100 and Nestin) and of the cytoskeletal proteins (GFAP and Vimentin) was evaluated by immunocytochemistry, as well as the cell viability by MTT test. The experimental results showed that the exposure to CW 900 MHz and AM 900 MHz was able to induce a significant decrease in cell viability, changes in morphology and expression of the analysed markers compared to the control cell cultures (incubator and sham). Surprisingly, these effects show a kinetic as function of exposure times and presence (AM 900 MHz) or absence (CW 900 MHz) of amplitude modulation. Studies are now in progress to better clarify the molecular mechanisms induced by EMF on OECs, in order to highlight also the involvement of glutamate receptors. References [1] Simkç M. et al., Quality Matters: Systematic Analysis of Endpoints Related to "Cellular Life" in Vitro Data of Radiofrequency Electromagnetic Field Exposure, Int J Environ Res Public Health 13(7), 701 (2016), doi: 10.3390/ijerph13070701. [2] Zeni O. et al., Induction of an adaptive response in human blood lymphocytes exposed to radiofrequency fields: influence of the universal mobile telecommunication system (UMTS) signal and the specific absorption rate. Mutat Res 747(1), 29-35 ( 2012). doi: 10.1016/j.mrgentox.2012.03.013. [3] Campisi A. et al., Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field, Neurosci Lett 473 52-5 (2010), doi: 10.1016/j.neulet.2010.02.018. [4] Pellitteri R. et al., Biomarkers expression in rat olfactory ensheathing cells, Front Biosci (Schol Ed) 2, 289-98 (2010).