Spatial gradient effects of 120 mT static magnetic field on endothelial tubular formation in vitro

This study investigated the spatial magnetic gradient effects of static magnetic fields (SMF) on endothelial tubular formation by applying the maximum spatial gradient to a target site of culture wells for cell growth. The respective maximum values of magnetic flux density (B(max)), magnetic flux gradient (G(max)) and the magnetic force product of the magnetic flux density and its gradient (a parameter of magnetic force) were 120 mT, 28 mT/mm and 1428 mT(2)/mm. The effects of gradient SMF on tubular formation were compared with those of uniform SMF that has no spatial gradients on the entire bottom area of culture wells. Five experimental groups of 25 samples each were examined: (1) sham exposure (control); (2) peak gradient exposure in the peripheral part; (3) peak gradient exposure in the central part; (4) uniform exposure to 20 mT; (5) uniform exposure to 120 mT. The SMF or sham exposure was carried out for 10 days. Photomicrographs of tubular cells, immunostained with an anti-platelet-endothelial cell adhesion molecule-1 (PECAM-1 [CD31]) antibody as a pan-endothelial marker, were analyzed after the 10-day culture. Gradient SMF in the peripheral or central part was found to significantly promote tubular formation in terms of the area density and length of tubules in each peak gradient/force part of the wells, compared with the sham exposure. In contrast, uniform SMF did not induce any significant change in the tubular formation. These findings suggest that tubule formation can be promoted by applying the peak gradient/force to a target site of culture wells.     

Effects of strong static magnetic fields used in magnetic resonance imaging on insulin-secreting cells

The magnetic flux density of MRI for clinical diagnosis has been steadily increasing. However, there remains very little biological data regarding the effect of strong static magnetic fields (SMFs) on human health. To evaluate the effects of strong SMFs on biological systems, we cultured insulin-secreting cells under exposure to sham and SMF conditions (3-10 T of magnetic flux density, and 0-41.7 T/m of magnetic field gradient) for 0.5 or 1 h, and analyzed insulin secretion, mRNA expression, glucose-stimulated insulin secretion, insulin content, cell proliferation and cell number. Exposure to SMF with a high magnetic field gradient for 1 h significantly increased insulin secretion and insulin 1 mRNA expression. Exposure to SMF with a high magnetic flux density for 0.5 h significantly enhanced responsiveness to glucose stimulation. Exposure to SMF did not affect the insulin content, cell proliferation or cell number. Our results suggested that MRI systems with a higher magnetic flux density might not cause cell proliferative or functional damages on insulin-secreting cells, and that SMF with a high magnetic field gradient might be used clinically after thorough in vivo investigations are conducted.     

Effects of static magnetic fields on the growth of various types of human cells

The effects of a static magnetic field (SMF) on the proliferation of various types of human cells were determined. All cultures were maintained at 37 °C throughout the experiment. SMF was generated by placing two magnets oppositely oriented on either side of a T25 flask. The flux density in the flask ranged from 35 to 120 mT. Growth curves were constructed by plotting cell number at 18 h and 4, 7, 11, and 14 days after seeding, with the 18‐h point being a measure of attachment efficiency. Exposure to SMF significantly decreased initial attachment of fibroblasts and decreased subsequent growth compared to sham‐exposed control. Significant effects were observed in both fetal lung (WI‐38) and adult skin fibroblasts, but they were generally larger in the fetal lung fibroblast line. SMF did not affect attachment of human melanoma cells, but inhibited their growth by 20% on day 7. SMF produced no effects in a human adult stem cell line. Oxidant production increased 37% in WI‐38 cells exposed to SMF (230–250 mT) during the first 18 h after seeding, when cell attachment occurs. Conversely, no elevation in oxidant levels was observed after a prolonged 5‐day exposure. These results indicate that exposure to SMF has significant biological effects in some, but not all types of human cells. Bioelectromagnetics 32:140–147, 2011. © 2010 Wiley‐Liss, Inc.     

Exposure to a MRI‐type high‐strength static magnetic field stimulates megakaryocytic/erythroid hematopoiesis in CD34+ cells from human placental and umbilical cord blood

The biological response after exposure to a high‐strength static magnetic field (SMF) has recently been widely discussed from the perspective of possible health benefits as well as potential adverse effects. To clarify this issue, CD34⁺ cells from human placental and umbilical cord blood were exposed under conditions of high‐strength SMF in vitro. The high‐strength SMF exposure system was comprised of a magnetic field generator with a helium‐free superconducting magnet with built‐in CO₂ incubator. Freshly prepared CD34⁺ cells were exposed to a 5 tesla (T) SMF with the strongest magnetic field gradient (41.7 T/m) or a 10 T SMF without magnetic field gradient for 4 or 16 h. In the harvested cells after exposure to 10 T SMF for 16 h, a significant increase of hematopoietic progenitors in the total burst‐forming unit erythroid‐ and megakaryocytic progenitor cells‐derived colony formation was observed, thus producing 1.72‐ and 1.77‐fold higher than the control, respectively. Furthermore, early hematopoiesis‐related and cell cycle‐related genes were found to be significantly up‐regulated by exposure to SMF. These results suggest that the 10 T SMF exposure may change gene expressions and result in the specific enhancement of megakaryocytic/erythroid progenitor (MEP) differentiation from pluripotent hematopoietic stem cells and/or the proliferation of bipotent MEP. Bioelectromagnetics 30:280–285, 2009. © 2009 Wiley‐Liss, Inc.     

Combined effect of X‐ray radiation and static magnetic fields on reactive oxygen species in rat lymphocytes in vitro

The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc.     

Various effects on transposition activity and survival of Escherichia coli cells due to different ELF-MF signals

Previous assays with weak sinusoidal magnetic fields (SMF) have shown that bacteria that had been exposed to a 50 Hz magnetic field (0.1–1 mT) gave colonies with significantly lower transposition activity as compared to sham-exposed bacteria. These experiments have now been extended by using a pulsed-square wave magnetic field (PMF) and, unexpectedly, it was found that bacteria exposed to PMF showed a higher transposition activity compared to the controls. The increase of the transposition activity was positively correlated with the intensity of the magnetic fields (linear dose-effect relation). This phenomenon was not affected by any bacterial cell proliferation, since no significant difference was observed in number and size of PMF-exposed and sham-exposed colonies. In addition, the cell viability of E. coli was significantly higher than that of the controls when exposed to SMF, and lower than that of the controls when exposed to PMF. Under our experimental conditions it was shown that exposure to PMF stimulates the transposition activity and reduces cell viability of bacteria, whereas exposure to SMF reduces the transposition mobility and enhances cell viability. These results suggest that the biological effects of magnetic fields may critically depend on the physical characteristics of the magnetic signal, in particular the wave shape.     

Investigation on the effect of static magnetic field up to 30 mT on viability percent,proliferation rate and IC50 of HeLa and fibroblast cells

Abstract

We have investigated the effects of static magnetic field (SMF) on the viability of the human cervical cancer (HeLa) cell line and fibroblast cells. The cells were cultured in DMEM medium and treated several times (24, 48,72 and 96?h) and at several intensities (5, 10, 20 and 30?mT) of magnetic field (MF). The cytotoxicity and cell viability percent in treated cells were performed using MTT assay by evaluating mitochondrial dehydrogenase activity. The MF ability on inducing cell death or inhibiting biochemical function was reported as cell death percent. The results showed that the increase of MF intensity and the time that cells were exposed to this treatment increased sharply cell death percent and proliferation rate in HeLa cell compare to fibroblast cells. Our data suggest that SMF biological effects on cell death were different in our selected targets. Cell type and time of exposure have been therefore found to be significant factors. These findings could be used to improve new effective method using SMF in conjunction with the common therapeutic approaches.     

磁场对红酵母的生长及类胡萝卜素合成的影响

考察直流电磁场对类胡萝卜素产生前红酵母RG-98的生长及代谢的影响。结果表明,不同的磁场强度、处理时间及处理方式会产生不同的生物效应。将液体种子和发酵培养基一起置于0.10T电磁场处理2h,能使色素的发酵产量提高25％。比较经磁场处理与未经处理的发酵过程,发现磁场处理提高了红酵母对糖的代谢速率,并且在发酵后期促进生物量和色素含量持续地增加。     

Static magnetic fields enhance skeletal muscle differentiation in vitro by improving myoblast alignment.

Static magnetic field (SMF) interacts with mammal skeletal muscle; however, SMF effects on skeletal muscle cells are poorly investigated. The myogenic cell line L6, an in vitro model of muscle development, was used to investigate the effect of a 80 +/- mT SMF generated by a custom-made magnet. SMF promoted myogenic cell differentiation and hypertrophy, i.e., increased accumulation of actin and myosin and formation of large multinucleated myotubes. The elevated number of nuclei per myotube was derived from increased cell fusion efficiency, with no changes in cell proliferation upon SMF exposure. No alterations in myogenin expression, a modulator of myogenesis, occurred upon SMF exposure. SMF induced cells to align in parallel bundles, an orientation conserved throughout differentiation. SMF stimulated formation of actin stress-fiber like structures. SMF rescued muscle differentiation in the presence of TNF, a muscle differentiation inhibitor. We believe this is the first report showing that SMF promotes myogenic differentiation and cell alignment, in the absence of any invasive manipulation. SMF-enhanced parallel orientation of myotubes is relevant to tissue engineering of a highly organized tissue such as skeletal muscle. SMF rescue of muscle differentiation in the presence of TNF may have important therapeutic implications.     

Static magnetic field with a strong magnetic field gradient (41.7 T/m) induces c-Jun expression in HL-60 cells

We investigated the effects of 6- and 10-T static magnetic fields (SMFs) on the expression of protooncogenes using Western blot immunohybridization methods. We used a SMF exposure system, which can expose cells to a spatially inhomogeneous 6 T with a strong magnetic field (MF) gradient (41.7 T/m) and a spatially homogeneous 10 T of the highest magnetic flux density in this experiment. HL-60 cells exposed to either 6- or 10-T SMF for periods of 1 to 48 h did not exhibit remarkable differences in levels of c-Myc and c-Fos protein expression, as compared with sham-exposed cells. In contrast, c-Jun protein expression increased in HL-60 cells after exposure to 6-T SMF for 24, 36, 48, and 72 h. These results suggest that a homogeneous 10-T SMF does not alter the expression of the c-jun, c-fos, and c-myc protooncogenes. However, our observation that exposure to a strong MF gradient induced c-Jun expression suggests that a strong MF gradient may have significant biological effects, particularly regarding processes related to an elevation of c-jun gene expression.     

Effects of a 300 mT static magnetic field on human umbilical vein endothelial cells

This study describes the effects of a static magnetic field (SMF) on cell growth and DNA integrity of human umbilical vein endothelial cells (HUVECs). Fast halo assay was used to investigate nuclear damage; quantitative polymerase chain reaction (QPCR), standard PCR, and real‐time PCR were used to evaluate mitochondrial DNA integrity, content, and gene expression. HUVECs were continually exposed to a 300 mT SMF for 4, 24, 48, and 72 h. Compared to control samples (unexposed cultures) the SMF‐exposed cells did not show a statistically significant change in their viability. Conversely, the static field was shown to be significant after 4 h of exposure, inducing damage on both the nuclear and mitochondrial levels, reducing mitochondrial content and increasing reactive oxygen species. Twenty‐four hours of exposure increased mitochondrial DNA content as well as expression of one of the main genes related to mitochondrial biogenesis. No significant differences between exposed and sham cultures were found after 48 and 72 h of exposure. The results suggest that a 300 mT SMF does not cause permanent DNA damage in HUVECs and stimulates a transient mitochondrial biogenesis. Bioelectromagnetics 31:630–639, 2010. © 2010 Wiley‐Liss, Inc.     

Assessment of the cyto- and genotoxic effects of a nanoferromagnetic and a static magnetic field in vivo

The cyto- and genotoxic effects of ferromagnetic nanoparticles (FNs), a static magnetic field (SMF), or their combination were comparatively studied in Ehrlich ascites carcinoma (EAC) cells, bone marrow (BM) erythroid series cells, and peripheral blood lymphocytes at definite time intervals, using the MN test and the DNA-comet assay. The MN test and the DNA-comet assay were used as markers of genotoxic exposure. It has been shown that the limit value of insignificantly expressed changes in the EAC cell architectonics (due to FNs) is an FN concentration of 3 mg/kg. The FN concentration increases in tumor cells, because the expressed blebbing in the cytoplasmic membrane increases the amount of micronuclei and the percentage of DNA in the comet tail in EAC cells, BM erythroid series cells, and peripheral blood lymphocytes. It has also been demonstrated that an SMF alone, as an independent factor, does not produce cytogenotoxic effects on the studied cells. When SMF and FN were used in combination, we could observe the phenomenon of SMF induction by FNs, which manifested itself as an increased total effect of these factors on cells. The MN-test and the DNA-comet assay can be used for assessing the genomic stability of both tumor cells and somatic nonmalignized cells when testing the genotoxic effect of nanomaterials used in the design of vector systems. As was established, the DNA-comet method demonstrated a higher sensitivity in the assessment of the genotoxicity produced by the studied factors.     

Modulatory effects of static magnetic fields on blood pressure in rabbits

Acute effects of locally applied static magnetic fields (SMF) on pharmacologically altered blood pressure (BP) in a central artery of the ear lobe of a conscious rabbit were evaluated. Hypotensive and vasodilator actions were induced by a Ca(2+) channel blocker, nicardipine (NIC). Hypertensive and vasoconstrictive actions were induced by a nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME). The hemodynamic changes in the artery exposed to SMF were measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, BP changes in a central artery contralateral to that of the exposed ear lobe were monitored. SMF intensity was 1 mT and the duration of exposure was 30 min. A total of 180 experimental trials were carried out in 34 healthy adult male rabbits weighing 2.6-3.8 kg. Six experimental procedures were chosen at random: (1) sham exposure without pharmacological treatment; (2) SMF exposure alone; (3) decreased BP induced by a single intravenous (iv) bolus injection of NIC (100 microM/kg) without SMF exposure; (4) decreased BP induced by injection of NIC with SMF exposure; (5) increased BP induced by a constant iv infusion of L-NAME (10 mM/kg/h) without SMF exposure; (6) increased BP induced by infusion of L-NAME with SMF exposure. The results demonstrated that SMF significantly reduced the vasodilatation with enhanced vasomotion and antagonized the reduction of BP via NIC-blocked Ca(2+) channels in vascular smooth muscle cells. In addition, SMF significantly attenuated the vasoconstriction and suppressed the elevation of BP via NOS inhibition in vascular endothelial cells and/or central nervous system neurons. These results suggest that these modulatory effects of SMF on BP might, in part, involve a feedback control system for alteration in NOS activity in conjunction with modulation of Ca(2+) dynamics.     

Mechanobiology of MG63 osteoblast-like cells adaptation to static magnetic forces

The aim of this study was to explore the biophysical effects of static magnetic field on osteoblastic cells. MG63 cells were exposed to 0.25 and 0.4-T static magnetic fields (SMF). The cell cycle effects were tested by flow cytometry. The differentiation of the cells was assessed by detecting the changes in prostaglandin E2, osteocalcin, and extracellular matrix expression. Membrane fluidity was used to evaluate the alterations in the biophysical properties of cellular membranes after the SMF simulations. Our results show that SMF exposure increases prostaglandin E2 level and extracellular matrix express in MG63 cells. On the other hand, MG63 cells exposed to 0.4-T SMF exhibited a significant decrease in membrane fluidity at 8 h. Based on these findings, it appears reasonable to suggest that SMF affect osteoblastic maturation by increasing membrane rigidity and then inducing differentiation pathway.     

Effects of static magnetic fields on the physical and chemical properties of cell culture medium RPM1 1640

RPMI 1640 culture medium was chosen to simulate body fluids, and after exposure to 0.085 approximately 0.092 T static magnetic fields (SMF), surface tension, pH, dissolved oxygen, and UV-visible spectrum were measured. Compared with the control group in the normal geomagnetic field, the pH value increased about 0.14 units, dissolved oxygen increased about 14%, and the UV-visible spectra were different in peak intensity but without a shift in the peak. Surface tension showed no significant difference in the two groups. This data suggests that SMF can change some of the physical and chemical properties of RPM1 1640 solution, and may contribute to understanding biological effects of SMF.     

Impact of Inhomogeneous Static Magnetic Field (31.7–232.0 mT) Exposure on Human Neuroblastoma SH-SY5Y Cells during Cisplatin Administration

Beneficial or adverse effects of Static Magnetic Fields (SMFs) are a large concern for the scientific community. In particular, the effect of SMF exposure during anticancer therapies still needs to be fully elucidated. Here, we evaluate the effects of SMF at induction levels that cisPt-treated cancer patients experience during the imaging process conducted in Low field (200–500 mT), Open field (300–700 mT) and/or inhomogeneous High field (1.5–3 T) Magnetic Resonance Imaging (MRI) machines. Human adrenergic neuroblastoma SH-SY5Y cells treated with 0.1 µM cisPt (i.e. the lowest concentration capable of inducing apoptosis) were exposed to SMF and their response was studied in vitro. Exposure of 0.1 µM cisPt-treated cells to SMF for 2 h decreased cell viability (30%) and caused overexpression of the apoptosis-related cleaved caspase-3 protein (46%). Furthermore, increase in ROS (Reactive Oxygen Species) production (23%) and reduction in the number of mitochondria vs controls were seen. The sole exposure of SMF for up to 24 h had no effect on cell viability but increased ROS production and modified cellular shape. On the other hand, the toxicity of cisPt was significantly prevented during 24 h exposure to SMF as shown by the levels of cell viability, cleaved caspase-3 and ROS production. In conclusion, due to the cytoprotective effect of 31.7–232.0 mT SMF on low-cisPt-concentration-treated SH-SY5Y cells, our data suggest that exposure to various sources of SMF in cancer patients under a cisPt regimen should be strictly controlled.     

The effect of 100 mT SMF on activation of the hsp70 promoter in a heat shock/luciferase reporter system

Human exposure to magnetic fields, increased through use of new technologies like magnetic resonance imaging (MRI), has prompted investigations into possible effects of static magnetic fields (SMFs) on cellular processes. However, controversy still remains between many studies, which likely results from a lack of uniformity across experimental parameters, including the length of magnetic field exposure, the strength of the magnetic field, and the cell type or organism under investigation. The purpose of this research was to monitor effects of SMF exposure using real‐time luminescence photometry. The study investigated the potential interaction of a 100 mT SMF on a heat shock protein (hsp70)/luciferase reporter construct in stably transfected NIH3T3 cells. Changes in heat shock promoter activation following 100 mT SMF exposure were analyzed and detected as bioluminescence in real‐time. Two heat parameters were considered in combination with sham‐ and 100 mT‐exposed experiments: no heat or 1,800 s heat. As expected, there was a significant increase in bioluminescence in response to 1,800 s of heat alone. However, no significant difference in average hsp70 promoter activation between sham and 100 mT experiments was observed for no heat or 1,800 s heat experiments. Therefore, a 100 mT SMF was shown to have no effect on the activation of the heat shock protein promoter during SMF exposure or when SMF exposure was combined with a heat insult. J. Cell. Biochem. 108: 956–962, 2009. © 2009 Wiley‐Liss, Inc.     

Biphasic effects of static magnetic fields on cutaneous microcirculation in rabbits

The biphasic effects of locally applied static magnetic fields (SMF) on the cutaneous microcirculation within a rabbit ear chamber (REC) were evaluated under conscious conditions. The microcirculatory vasomotion within a REC was measured continuously and analyzed multilaterally by microphotoelectric plethysmography, a real-time image analyzer and an image shearing monitor. SMF intensities at the REC were controlled at 1 mT and the duration of exposure was 10 min. Seventy-eight experimental trials were carried out on 22 healthy adult rabbits weighing 2.6-3.5 kg. Five experimental groups were chosen at random: 1) no pharmacological treatment or SMF exposure, 2) increased vascular tone induced by noradrenaline infusion without SMF exposure, 3) increased vascular tone induced by noradrenaline infusion with SMF exposure, 4) decreased vascular tone induced by acetylcholine infusion without SMF exposure, 5) decreased vascular tone induced by acetylcholine infusion with SMF exposure. The results demonstrated that SMF significantly enhanced vasodilatation, with increased vasomotion under noradrenaline-induced high vascular tone as well as vasoconstriction with reduced vasomotion under acetylcholine-induced low vascular tone. This suggests, therefore, that SMF can modulate vascular tone due to biphasic modification of vasomotion in the cutaneous tissue.     

Myotube orientation using strong static magnetic fields

In this experiment, we evaluated the effects of strong static magnetic fields (SMF) on the orientation of myotubes formed from a mouse-derived myoblast cell line, C2C12. Myogenic differentiation of C2C12 cells was conducted under exposure to SMF at a magnetic flux density of 0-10 T and a magnetic gradient of 0-41.7 T/m. Exposure to SMF at 10 T led to significant formation of oriented myotubes. Under the high magnetic field gradient and a high value of the product of the magnetic flux density and magnetic field gradient, myotube orientation increased as the myogenic differentiation period increased. At the 3 T exposure position, where there was a moderate magnetic flux density and moderate magnetic field gradient, myotube orientation was not observed. We demonstrated that SMF induced the formation of oriented myotubes depending on the magnetic flux density, and that a high magnetic field gradient and a high value of the product of the magnetic flux density and magnetic field gradient induced the formation of oriented myotubes 6 days after myogenic differentiation. We did not detect any effect of the static magnetic fields on myogenic differentiation or cell number. To the best of our knowledge, this is the first report to demonstrate that myotubes orient to each other under a SMF without affecting the cell number and myogenic differentiation.