MINI LITERATURE REVIEW: THE LITERATURE REVIEW OF ELECTRICITY EFFECTS ON CELL PHYSIOLOGY AND RELATED NEW ELECTRICAL TREATMENT MODALITIES

This paper is a literature review about electromagnetic field ’ s effects on cells, tissues and new treatment modalities. We have compiled the papers which have been published in well qualited journals in the last 5 years as two authors. This review ’s aim is to be a resource for experimental studies about electricity ’s effect s on cell biology and pathophysiology. As a result of literature review, we found that especially extremely low electric frequency and intermediate frequency fields have very important pathophysiological effects. We have mentioned about four important expressions on this subject; electroporation, electrofusion, electrochemotherapy, gene electrotransference. Two different new treatment approaches have been developed by use of these two important frequency waves. First is tumor treating fields and the other is pulsed electric fields. Most studies in literature have been done with extremely low frequency and pulsed electric fields. In terms of diseases, most studies are about glioblastoma and melanoma.


INTRODUCTION
In this paper, it was our goal to make literature research what kind of effect each frequency of electricity has on cells and human tissues and explain new electrical treatment modalities. This paper draw attention the physiological changes in which the electricity generally produces biological effects and the pathological events especially in cancer, potential therapeutic effects. Most studies in literature have been done with extremely low frequency and pulsed electric fields. In terms of diseases, most studies are with glioblastoma and melanoma.
The two most important frequencies mentioned in the literature are extremely low frequency and intermediate frequency electric waves. Two different new treatment approaches have been developed by making use of these two important frequency waves. First is tumor treating fields and the other is pulsed electric fields.
Firstly, we will discuss about the biological effects of these waves in general and the studies on this subject in the literature. Secondly we will discuss about terms about this topic. This paper draws attention to some unknown important cellular effects of electricity, and these effects are likely to create new treatment modalities. After more than a hundred articles we have scanned, we have confirmed that cancer cells are damaged and disrupted under a low-frequency electric field. We will explain these studies later in this article. In addition, we will talk about the four most important terms mentioned in the articles on this subject; Electroporation, electrochemotherapy, electrofusion, gene electrotansfer. This paper is a up-to-date article written on this subject, but it will be a great resource for beginners.

METHODS
We have scanned as '((Electricity) AND (Frequency)) OR (Disease)' OR (ELF) OR (EMF) OR (Mangetic) OR (Galvanotaxic) OR (Electroporation) OR (TTF) OR (PEF) from PubMed and we have selected 30 of that 300 articles, which publicated in the high quality journals.

History of Electricity and First Researchs about Its Biological Effects
An electric field is be formed by charged particles. Electric fields are discussed in physics, electrostatics and electrodynamics. Electrostatics is related to unchanged electric fields; electrodynamics is related to changes in electric fields. In addition, electrical fields have an effect on magnetic current. Electric currents can be used to generate a magnetic field, and magnetic fields can be used to generate an electric current. The electric field equation is defined as E = F / q, in which E represents the energy of the electric field, F represents the power of the particle, and q represents the charge of the particle. The force of an electric field is the units named in honor of Newton and Charles-Augustin de Coulomb. The Danish physicist and chemist Hans Christian Oersted (1777-1851) was the first one who noticed the electric fields are affecting magnetism while teaching a course at the University of Copenhagen. When he passed an electric wire over a magnetic compass, he noticed that the compass needle was moving. He then made experiments that confirmed the relationship between electricity and magnetism, which showed that electric fields have a magnetic effect. Electric fields and magnetic fields were intertwined. Faraday's work was extended by the Scottish mathematician James Clerk Maxwell (1831-79), who elaborated the relationship between electricity and magnetism. Maxwell's equations, built on Faraday's law, clearly state the relationship between magnetism and electricity and show how magnetism and electricity interact individually and how they interact with each other. Maxwell's equations are the cornerstone of electromagnetic theory. (1) Galvani proved that there is electricity in living things by showing the sciatic nerve by touching the muscle of a frog by showing its muscle twitching. However, scientists had to wait until the 1940s to prove that there was an electrical potential in their membranes, and that some cells (excitable cells such as nerve and muscle) could quickly change this potential to create an action potential. The reason for this was that the cells studied were very narrow in diameter (20 μ), but the electrodes connected to electronic devices had a much larger tip diameter. Galvani's work was confirmed by the creation of new instruments and the interest of new scientists, leading him to be regarded as the father of electrophysiology. (2) After thorough research, a large-scale nerve cell was found in cuttlefish. Hodgkin and Huxley demonstrated the presence of membrane potential in the cell membrane for the first time by introducing electrodes into the giant nerve fiber (approximately 1000 μ diameter) of this fish. According to this measure, there was a potential difference of approximately -70 mV between the inside and outside of a nerve cell, even at rest. (3) The passage of matter through the cell membrane, a barrier separating the cell from the external environment, is by diffusion. The membrane potential in all cells is between 60 and 90 mV in excitable cells such as nerve and muscle. Membrane potential found in all living cells may change temporarily in some cells and become temporary (action) potential. (4)

Intermediate Frequency and Extremely Low Frequency Electric Field's Pathopsyhological Effects
In general, there are two different wave types in the literature. These are extremely low frequency fields and intermediate frequency fields. The effects of these two on the biologic cells are very diffrent. Using these effects, new treatment methods have been developed. Firstly, we will discuss about the biological effects of these waves in general and the studies on this subject in the literature.
For one research electric field's pathological effects on tumor cells are Significant slowdown in tumor growth in the electric field of 100-300 KHZ (intermediate frequency) and extensive destruction of tumor cells within 3-6 days. The first effect is on the mitotic cycle, the second effect is a sudden disintegration of the cell. These effects occur in 24 hours per day in 3-6 days. This research has been tested in animal malignant tumors and cell cultures. (5) For one experimental study, interestingly, in contrast to the highly metastatic rat prostate cancer cell line, a weak metastatic cell line did not respond at similar EF strengths. (6) These waves can be used in the treatment of cancer, and although it is controversial, it can be a cause of cancer. It was observed that childhood leukemia increases with in the region's of strong electric fields. There are many supporting studies similar to this. (7) Chronic 60 hertz electric field (30 days, 20 hours a day) When applied to reduce the production of pineal gland melatonin, it reduces to zero. As a result, estrogen production increases (melatonin suppresses estrogen production) and hence the mass or cancer in the breast grows. (8) It applies an oscillating force to each of the free ions of an oscillating external electric field, which is located on both sides of the membrane transition proteins. This external oscillation force causes a forced vibration of each free ion. When the forced vibration of the ions exceeds some critical amplitude, the pulsating ions may give a false signal to open and close the voltage-gated (even mechanically gated) channels, the disrupting the electrochemical balance of the plasma membrane and ultimately terminating the whole cell function. (9) At medium frequency, the low-density electric field inhibits mitosis cleavage by exhibiting antimicrotubular properties. (10,11) ELFs have direct effects at the level of the cell membrane. They induce redistribution of membrane receptors for transferrin and low-density lipoprotein. It was concluded that each hair cell contains its own electrical resonance mechanism, which constitutes most of the frequency selectivity of the receptor potential.  13) The pores are larger under low ionic conditions and allow sucrose molecules to pass, but under no circumstances can hemoglobin pass as a direct result of the voltage pulse. Because it's a big molecule. Kinetic measurements show that hemolysis of erythrocytes follows a step-by-step mechanism: leakage of ions leads to an osmotic imbalance, leading to a colloidal hemolysis of red cells. (14,15,16) Literature datas show that the ELF (extremely low electrical field) reduces the level of lipid peroxide in an oxidative stress rat. (17) The properties tissue electricity are likely to change in malignancies. Prostate adenocarcinoma can be treated with electrotherapy. Because the malignant cells are strong galvanotactic, can remove the diseased gland by applying small dc voltages. (18,19,20) The electrical frequency of most cells in human tissues are different. For example, slow oscillations at theta frequencies (4-12 Hz) are consistently recorded in the hippocampus during working tasks, spatial navigation, and storage of episodic memory. The hippocampus is capable of generating its own theta rhythm when isolated in vitro Another treatment hypothesis in this regard is to destroy the cell by resonating the cell with electrical frequency matching. (21)

Pulsed Electromangetic Field Therapy (Extremely low frequency)
ELF-Pulsed electromagnetic field therapy (PEMFT) uses extremely low frequency electromagnetic fields in an attempt to especially glioblastoma, fractures and depression. By 2007 the FDA had approved several such stimulation devices.
Unlike TTF, pulsed electromangetic fields have been done in many more areas. There are many promising studies on depression and fracture, postoperative pain.
PEMF upregulates X-linked inhibitor of apoptosis, which is considered the most potent caspase inhibitor. (22) PEF (Pulsed electric fields) causes cell and organelle disruption in many cells. (23) In one PEF study ;cells were exposed to external direct current electric fields with physiological force, their reactions were recorded by light microscopy and analyzed by a quantitative monitoring method. Voltage-gated Na + channel activity was pharmacologically modulated using a specific channel blocker (tetrodotoxin) or opener (veratridine) concentrations. (24,25,26,27) The results showed that high metastatic MAT-LyLu cells (Na-K channel open or excess) reacted very strongly to the application of the electric field by migrating to the cathode. In contrast, weak metastatic At-2 cells (with NA-K channel closed) did't respond to this. (28) One electrical model for biological cells has allowed us to predict that the electrical field interaction with intracellular structures is increased in pulses that last longer than the charging time of the outer membrane. Experimental studies in which human cells were exposed to pulsed electric fields up to 300 nV / cm amplitude, as short as 10 ns, confirmed this hypothesis.(PEF) The observed effects are the degradation of intracellular granule membranes without permanent damage to the cell membrane, abrupt increases in intracellular free calcium levels and increased expression of genes. In increasing electric fields, the application of submicron second envelopes evokes apoptosis (programmed cell death) in biological cells, which has been shown to reduce the growth of tumors. The possible effects of intracellular electro-effect are controlling gene function in the nucleus, controlling cell function due to calcium release (which causes cell immobilization) and regressing tumors. (29) To summarize nanosecond pulsed electrical effects on endothelial cell's data, appropriate pulse parameters are able to enhance cell proliferation on endothelial cells which may involve the intracellular kalsiyum concertation, as well as ROS and NO production in nsPEFs treatment system. Some results suggest that nsPEFs may have a potential application in the process of accelerating the stent endothelialization. (30)

Tumor Treating Fields (TTF)
Tumor treating field is low intensity and intermediate frequency (200 kHz) alternating electric fields, which have been demonstrated to disrupt mitosis, induce cell arrest, induce apoptosis with antimitotic properties in a variety of tumor types. (31) A clinical TTF device is approved in the United States and Europe for the treatment of recurrent glioblastoma. The device can be used in conjunction with regular patterns of care for patients, but are only available in certain treatment centers, and specific training and certification on the part of the prescribing physician. (32) It has recently been shown in some researchs that low density, intermediate frequency and electric fields inhibit cancer cell growth by an in vitro anti-microtubule mechanism of action. By using implanted electrodes, tumor areas were also shown to inhibit the growth of dermal tumors in mice.(TTF) This study extends these findings to additional cell lines and animal tumor models using externally isolated electrodes. (33,34,35) These findings have led to the initiation of a pilot clinical trial of the effects of TT fields in 10 patients with recurrent glioblastoma (GBM). In terms of disease progression, this time is normally more than twice the life expectancy. The only side effect was mild contact dermatitis. (TT fields = tumor treating fields) (36,37,38,39,40,41) TTF is selectively toxic to proliferating cells via an anti-mitotic mechanism has been widely reported. (42) This may prevent damage to other cells.

Membrane Electroporation Phenomenon
It is the change in the membrane permeability of the cells in the electric field. Therapeutic models are currently being developed using this phenomenon. Electrochemotherapy is a new therapeutic option for patients with locally spread melanoma. It is based on the phenomenon of reversible electroporation. It was showed in vitro, that electroporation can prompt the formation of reactive oxygen species (ROS) near cell membranes, which can be detrimental to cell viability. (43,44,45) Electrochemotherapy Electrochemotherapy (ECT) is a locally chemotherapy that combines the administration of chemotherapeutic drugs with electric pulses for cell membrane electroporation (EP). Electroporation is a well-known phenomenon that occurs at the cell membrane when cells are exposed to high intensity electric pulses. Reversible electroporation is used to introduce drugs or genetic material into the cell without affecting cell viability. Electrochemotherapy refers to a combined treatment; electroporation and drug injection to enhance its cytotoxic effect. (46,47)

Electrofusion
Cell electrofusion is a safe method that can be used for preparing hybrid cells for human therapy. Electrofusion involves application of short high-voltage electric pulses to cells that are in close contact. Application of short, high-voltage electric pulses causes destabilization of cell plasma membranes. Destabilized membranes are more permeable for different molecules and also prone to fusion with any neighboring destabilized membranes. Electrofusion is a convenient method to achieve a fusion of very different cells in vitro. (48)

Gene Electrotransference
For some diseases, if gene therapy is performed using an electrical effect, it is called gene electrotransference. Another application of electroporation is the clinical trials that have been achieved, where electroporation is used for transfection of cells within tissues with plasmid DNA, for the purpose of cancer therapy. (49,50,51) 3.CONCLUSIONS As a result, we discussed the effects of electricity on cell in general with new treatment methods. The effects of electricity on cells are very important for medicine . New treatment models were made using these effects.
As a result of literature review, we found that especially extremely low electric frequency and intermediate frequency fields have very important pathophysiological effects. We have mentioned about four important expressions on this subject; electroporation, electrofusion, electrochemotherapy, gene electrotransference. Two different new treatment approaches have been developed by making use of these two important frequency waves. First is tumor treating fields and the other is pulsed electric fields.
The findings in this article will provide up-to-date information on new studies on antioxidane system, atherosclerosis and especially tumor treatment. This paper will help to find some new treatment methods in the future.
In future studies, we aim to prevent the chemically damaged, uncontrolled division of tumors by electrical resonance, or otherwise possible division. After dozens of articles, we have confirmed that cancer cells are damaged and damaged under low frequency electric and pulsed electric field.
In general, we concluded that electrical fields have important physiological effects on cell biology. We hope that the topics discussed in detail in the discussion section will provide a basic source of information for future studies.