# The Biocompatibility of Wireless Power Charging System on Human Neural Cells
## 4 Discussion
After exposure, cells were regenerated for another 44 h at standard cultivation condition to see the possible cumulative negative impact of EMF on cells. Based on our set conditions, we were not able to detect any diverse effect on cell morphology, viability, or cytoskeletal disintegration at 87 kHz, 1.2 mT for 30 min. Several studies have analyzed electric, magnetic and EMF exposure effect, obtaining the most diverse outcomes [1; 15]. Most of the studies were performed using cell or animal models. They have provided basic information on the possible biological effects of EMF exposure to living systems. There are few studies focused on the acute or chronic EMF exposure in IF range and its consequence on human health at cellular level in vitro [45; 46; 47]. Therefore, the investigation of potential adverse or cumulative EMF effect is quite challenging and precise epidemiological studies are needed to confirm the possible negative effects of EMF exposure to humans [15]. Moreover, the technology of the WTP system (85 kHz) was studied on human body models [48]. They evaluated the induced electric field in the human body models for a magnetic field leaked from a WPT system in an electrical vehicle. The induced electric fields in three anatomically based human body models were weaker than the basic restriction, although the external magnetic field exceeded the reference level. Even though these observations are supporting, it is necessary to verify their impact on living systems. During our analysis, we did not observe any changes in cell morphology as well as in number of cells (Figure 10). The tested conditions did not have any negative impact on cell division on healthy normal cells, HA. We even did not find any dead cells accumulated in cancer cell lines and did not prove the apoptosis activated after exposure. Some papers observed altered cell metabolism or cell adhesion associated with changes in cell morphology [49; 50]. Even though, the effect on calcium efflux and cell differentiation were also proved [51; 52]. On the other hand, several in vitro studies did not find any significant effect of EMF exposure on cell differentiation, neither on phagocytosis or chemotaxis [53; 54]. Alteration of proliferation is a sensitive indication that could be used to identify any cytotoxic impact. The effect of EMF on cell viability was analyzed spectrophotometrically by MTT test (Figure 11). Considering our results, cell viability after exposure to 87 kHz at 0.3-1.2 mT of EMF for 30 min did not appear to have an adverse effect on HA, SH-SY5Y or T98G cell lines. HA showed a little increase in cell viability, however, these changes were not statistically significant. Some in vitro studies were focused on the effect of MF on cell proliferation and viability. However, the outcomes were different, as these studies detected reduced or increased cell growth and viability, as well [23; 41; 45]. It has been shown that external EMF can induce a variety of molecular and cellular responses, including microfilament reorganization, changes in calcium dynamics, neuronal growth cone guidance or enhanced stem cell differentiation [55]. Even though electrotherapy has been successfully used for nerve fiber repair, bone fracture treatment or cancer chemotherapy, little information is known about the effect of IF-EMF on the cell mechanical properties [56]. The cytoskeleton is one of the most significant cellular mechanical structures that allow elasticity and stability of the cell undergoing multiple deformations without losing its integrity. In addition, the important role of the cytoskeleton has been established in complex intracellular signaling pathways. It mediates cell responses, as changes in cell adhesion or in gene expression and secretion of extracellular matrix by itself structural rearrangement alterations [57]. Our results did not show any changes in actin filaments organization in normal human astrocytes. Even though, there was not any detrimental effect of 87 kHz EMF on cytoskeletal structures of cancer cells.