Frequency Pulsed Electromagnetic Fields Research Articles

Extremely low frequency pulsed electromagnetic fields cause antioxidative defense mechanisms in human osteoblasts via induction of \u2022O2\u2212 and H2O2

Recently, we identified a specific extremely low-frequency pulsed electromagnetic field (ELF-PEMF) that supports human osteoblast (hOBs) function in an ERK1/2-dependent manner, suggesting reactive oxygen species (ROS) being key regulators in this process. Thus, this study aimed at investigating how ELF-PEMF exposure can modulate hOBs function via ROS. Our results show that single exposure to ELF-PEMF induced ROS production in hOBs, without reducing intracellular glutathione. Repetitive exposure (>3) to ELF-PEMF however reduced ROS-levels, suggesting alterations in the cells antioxidative stress response. The main ROS induced by ELF-PEMF were •O2− and H2O2, therefore expression/activity of antioxidative enzymes related to these ROS were further investigated. ELF-PEMF exposure induced expression of GPX3, SOD2, CAT and GSR on mRNA, protein and enzyme activity level. Scavenging •O2− and H2O2 diminished the ELF-PEMF effect on hOBs function (AP activity and mineralization). Challenging the hOBs with low amounts of H2O2 on the other hand improved hOBs function. In summary, our data show that ELF-PEMF treatment favors differentiation of hOBs by producing non-toxic amounts of ROS, which induces antioxidative defense mechanisms in these cells. Thus, ELF-PEMF treatment might represent an interesting adjunct to conventional therapy supporting bone formation under oxidative stress conditions, e.g. during fracture healing.

Osteogenic differentiation potential of mesenchymal stem cells cultured on nanofibrous scaffold improved in the presence of pulsed electromagnetic field.

Nowadays, tissue engineering by using stem cells in combination with scaffolds and bioactive molecules has made significant contributions to the regeneration of damaged bone tissues. Since the usage of bioactive molecules including, growth factors to induce differentiation is safety limited in clinical applications, and it has also been previously observed that extremely low frequency pulsed electromagnetic fields (PEMF) can be effective in the enhancement of proliferation rate and osteogenic differentiation of stem cells, the aim of this study was investigating the osteoinductive potential of PEMF in combination with Poly(caprolactone) (PCL) nanofibrous scaffold. To achieve this aim, Adipose-derived mesenchymal stem cells (ADSCs) isolated and characterized and then osteogenic differentiation of them was investigated after culturing on the surface of PCL scaffold under treatments of PEMF, PEMF plus osteogenic medium (OM) and OM. Analysis of common osteogenic markers such as Alizarin red staining, ALP activity, calcium content and four important bone-related genes in days of 7, 14, and 21 confirmed that the effects of PEMF on the osteogenic differentiation of ADSCs are very similar to the effects of osteogenic medium. Thus, regarding the immunological concerns about the application of bioactive molecules for tissue engineering, PEMF could be a good alternative for osteogenic medium. Although, results were showed a synergetic effect for simultaneous application of PEMF and PCL scaffold in the osteogenesis process of ADSCs. Taking together, ADSCs-seeded PCL nanofibrous scaffold in combination with PEMF could be a great option for use in bone tissue engineering applications.

Management of diabetic peripheral neuropathy (DPN) using low frequency pulsed electro magnetic field (LF-PEMF)

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract #272: Management of Diabetic Peripheral Neuropathy (DPN) Using Low Frequency Pulsed Electro Magnetic Field (LF - PEMF)

Abstract #272: Management of Diabetic Peripheral Neuropathy (DPN) Using Low Frequency Pulsed Electro Magnetic Field (LF - PEMF)

Low frequency pulsed electromagnetic field promotes C2C12 myoblasts proliferation via activation of MAPK/ERK pathway

Low frequency pulsed electromagnetic field (PEMF) has been shown to affect the activity of various cell types and promote them proliferation. However, its effect on skeletal muscle cells remains to be determined. In our study, we confirmed that PEMF (100 Hz, 1 mT) could promote C2C12 myoblasts proliferation by using Cell Counting Kit-8 (CCK-8) and 5-Ethynyl-2’-deoxyuridine (EdU) assays, yet hardly any distinction was found in the rate of cell apoptosis between PEMF and control groups by flow cytometry (Annexin V-FITC/PI double staining method). To further study the mechanism of action of PEMF, Western blot was utilized to detect the mitogen-activated protein kinase (MAPK) signaling pathways. After exposing C2C12 myoblasts to PEMF, we found the phosphorylation level of extracellular signal-regulated kinase (ERK) was significantly increased, while p38 MAPK and c-Jun N-terminal kinase (JNK) pathways were not affected. Pretreating the cells with the ERK kinase1/2 (MEK1/2) inhibitor U0126 obviously inhibited the proliferation of C2C12 cells. Taken together, our research for the first time demonstrated that PEMF promoted C2C12 myoblasts proliferation via activating MAPK/ERK pathway.

Short-term effects of extremely low-frequency pulsed electromagnetic field and pulsed low-level laser therapy on rabbit model of corneal alkali burn

This study was conducted to investigate the effect of combining extremely low frequency–pulsed electromagnetic field (ELF-PEMF) and low-level laser therapy (LLLT) on alkali-burned rabbit corneas. Fifty alkali-burned corneas of 50 rabbits were categorized into five groups: ELF-PEMF therapy with 2 mT intensity (ELF 2) for 2 h daily; LLLT for 30 min twice daily; combined ELF-PEMF and LLLT (ELF + LLLT); medical therapy (MT); and control (i.e., no treatment). Clinical examination and digital photography of the corneas were performed on days 0, 2, 7, and 14. After euthanizing the rabbits, the affected eyes were evaluated by histopathology. The clinical and histopathologic results were compared between the groups. On days 7 and 14, no significant difference in the corneal defect area was evident between the ELF, LLLT, ELF + LLLT, and MT groups. Excluding the controls, none of the study groups demonstrated a significant corneal neovascularization in both routine histopathology and immunohistochemistry for CD31. Keratocyte loss was significantly higher in the MT group than in the ELF, LLLT, and ELF + LLLT groups. Moderate to severe stromal inflammation in the LLLT group was comparable with that in the MT group and was significantly lower than that in the other groups. In conclusion, combining LLLT and ELF was not superior to ELF alone or LLLT alone in healing corneal alkali burns. However, given the lower intensity of corneal inflammation and the lower rate of keratocytes loss with LLLT, this treatment may be superior to other proposed treatment modalities for healing alkali-burned corneas.

ELF-EMF exposure decreases the peroxidase catalytic efficiency in vitro

AbstractThe activity of purified Fe3+ containing horseradish peroxidase (HRP) was recorded while the enzyme was exposed to two low frequency pulsed electromagnetic fields (ELF-EMFs) with different frequencies: 50 Hz/2.7 mT and 100 Hz/5.5 mT. No statistically significant difference in the Michaelis constant (Km) values between the control enzyme and the enzyme exposed to any of the two ELF-EMF used could be detected (53 ± 11 μM vs 67 ± 10 μM vs 42 ± 11 μM respectively), indicating that upon short exposure times, there are no large structural alterations of the enzyme that affect the substrate affinity. A 50 Hz/2.7 mT EMF did however, cause a significant decrease in the maximum rate (Vmax) value (from 3.31 ± 0.17 μmoles/min to 1.6 ± 0.19 μmoles/min, p<0.03) and a drop of the catalytic efficiency to less than half (from 0.66 ± 0.03 s-1 to 0.32 ± 0.04 s-1, p<0.05). These observations are the first experimental proofs that support the previously postulated mechanism of coupling between ELF-EMF and living systems based on a resonant frequency specific for a given ion molecule.

Efficacy of physical therapy for the treatment of lateral epicondylitis: a meta-analysis.

BackgroundPhysical therapy for the treatment of lateral epicondylitis (LE) often comprises movement therapies, extracorporeal shockwave therapy (ECSWT), low level laser therapy (LLLT), low frequency electrical stimulation or pulsed electromagnetic fields. Still, only ECSWT and LLLT have been meta-analytically researched.MethodsPUBMED, EMBASE and Cochrane database were systematically searched for randomized controlled trials (RCTs). Methodological quality of each study was rated with an adapted version of the Scottish Intercollegiate Guidelines Network (SIGN) checklist. Pain reduction (the difference between treatment and control groups at the end of trials) and pain relief (the change in pain from baseline to the end of trials) were calculated with mean differences (MD) and 95 %-Confidence intervals (95 % CI).ResultsOne thousand one hundred thirty eight studies were identified. One thousand seventy of those did not meet inclusion criteria. After full articles were retrieved 16 studies met inclusion criteria and 12 studies reported comparable outcome variables. Analyses were conducted for overall pain relief, pain relief during maximum handgrip strength tests, and maximum handgrip strength. There were not enough studies to conduct an analysis of physical function or other outcome variables.ConclusionsDifferences between treatment and control groups were larger than differences between treatments. Control group gains were 50 to 66 % as high as treatment group gains. Still, only treatment groups with their combination of therapy specific and non-therapy specific factors reliably met criteria for clinical relevance. Results are discussed with respect to stability and their potential meaning for the use of non-therapy specific agents to optimize patients’ gain.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0665-4) contains supplementary material, which is available to authorized users.

Primary human osteoblasts with reduced alkaline phosphatase and matrix mineralization baseline capacity are responsive to extremely low frequency pulsed electromagnetic field exposure — Clinical implication possible

For many years electromagnetic fields (EMFs) have been used clinically with various settings as an exogenous stimulation method to promote fracture healing. However, underlying mechanisms of action and EMF parameters responsible for certain effects remain unclear. Our aim was to investigate the influence of defined EMFs on human osteoblasts' and osteoclasts' viability and function. Primary human osteoblasts and osteoclasts were treated 3 times weekly for 21days during their maturation process using the Somagen® device (Sachtleben GmbH, Hamburg, Germany), generating defined extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs). Certain ELF-PEMF treatment significantly increased the total protein content (up to 66%), mitochondrial activity (up to 91.1%) and alkaline phosphatase (AP) activity (up to 129.9%) of human osteoblasts during the entire differentiation process. Furthermore, ELF-PEMF treatment enhanced formation of mineralized matrix (up to 276%). Interestingly, ELF-PEMF dependent induction of AP activity and matrix mineralization was strongly donor dependent — only osteoblasts with a poor initial osteoblast function responded to the ELF-PEMF treatment. As a possible regulatory mechanism, activation of the ERK1/2 signaling pathway was identified. Maturation of osteoclasts from human monocytes was not affected by the ELF-PEMF treatment. In summary the results indicate that a specific ELF-PEMF treatment with the Somagen® device improves viability and maturation of osteoblasts, while osteoclast viability and maturation was not affected. Hence, ELF-PEMF might represent an interesting adjunct to conventional therapy supporting bone formation during fracture healing or even for the treatment of osteoporosis.

Irradiation of Escherichia coli by extremely-low frequency (ELF) pulsed electromagnetic fields (PEMF): evaluation of bacterial survival

The effects of extremely low-frequency (ELF) pulsed electromagnetic field (PEMF) emitted by the custom-build exposure chamber on the growth and survival of the bacterium Escherichia coli (E. coli ATCC 25922) have been studied. The viability of E. coli was measured as colony-forming units (CFUs) before and after the exposures at frequencies, f, 2–500 Hz and magnetic flux densities, B, 2.5–5 mT to quantify the effects of applied ELF PEMF on these bacteria. The maximum reduction in bacterial growth was observed with the exposures at 3 Hz and 0.5 mT. The maximum decrease in CFU was recorded for the exposure at 500 Hz and 2.5 mT, which corresponds to a relative decrease of 77.26% in the bacterial growth. Findings from this study have direct implication for determining the optimal characteristics of the applied ELF PEMF for possible treatment of infected tissue and thus, wound healing promotion.

Combined effect of constant high voltage electrostatic field and variable frequency pulsed electromagnetic field on the morphology of calcium carbonate scale in circulating cooling water systems.

Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed.

Low Intensity and Frequency Pulsed Electromagnetic Fields Selectively Impair Breast Cancer Cell Viability

IntroductionA common drawback of many anticancer therapies is non-specificity in action of killing. We investigated the potential of ultra-low intensity and frequency pulsed electromagnetic fields (PEMFs) to kill breast cancer cells. Our criteria to accept this technology as a potentially valid therapeutic approach were: 1) cytotoxicity to breast cancer cells and; 2) that the designed fields proved innocuous to healthy cell classes that would be exposed to the PEMFs during clinical treatment.MethodsMCF7 breast cancer cells and their normal counterparts, MCF10 cells, were exposed to PEMFs and cytotoxic indices measured in order to design PEMF paradigms that best kill breast cancer cells. The PEMF parameters tested were: 1) frequencies ranging from 20 to 50 Hz; 2) intensities ranging from 2 mT to 5 mT and; 3) exposure durations ranging from 30 to 90 minutes per day for up to three days to determine the optimum parameters for selective cancer cell killing.ResultsWe observed a discrete window of vulnerability of MCF7 cells to PEMFs of 20 Hz frequency, 3 mT magnitude and exposure duration of 60 minutes per day. The cell damage accrued in response to PEMFs increased with time and gained significance after three days of consecutive daily exposure. By contrast, the PEMFs parameters determined to be most cytotoxic to breast cancer MCF-7 cells were not damaging to normal MCF-10 cells.ConclusionBased on our data it appears that PEMF-based anticancer strategies may represent a new therapeutic approach to treat breast cancer without affecting normal tissues in a manner that is non-invasive and can be potentially combined with existing anti-cancer treatments.

Evaluation of the effects of Extremely Low Frequency (ELF) Pulsed Electromagnetic Fields (PEMF) on survival of the bacterium Staphylococcus aureus

BackgroundThis study investigated the effects of extremely low frequency (ELF) pulsed electromagnetic field (PEMF) radiation on the growth of bacterium Staphylococcus aureus (ATCC 25923) that plays a versatile role in infecting wounded tissues. The viability of these bacteria (number of live cells as colony-forming units (CFUs)) was measured before and after the ELF PEMF exposures to quantify their survival rate.MethodsS. aureus cultures were first cultivated in an agar medium, and then picked and suspended in Columbia broth medium. Optical density reading for the suspended bacteria was measured at 600 nm and adjusted to a specific value of 0.1 ± .005A prior to experimentation and placement of bacteria into 2.5 mL centrifuge tubes. Sham-exposed tubes filled with bacteria were kept under the same experimental conditions and used as controls. The constructed exposure system, emitting uniform time varying magnetic fields (frequency of 2-500 Hz, and magnetic induction of 0.5-2.5 mT), was employed to irradiate S. aureus bacteria for 90 min. To determine the CFU per ml of the exposed bacteria, five serial dilutions were performed. A volume of 100 μl from the last tube was suspended onto agar plates by spread plating. After incubation, the colonies formed on the plates were visually counted.ResultsAll irradiated S. aureus bacteria showed decrease in their growth rate compared to control samples. The results demonstrated that ELF PEMF exposures at 150-500 Hz are more effective than exposures at 3-100 Hz in reducing the viability of S. aureus in broth. The lowest CFU value was achieved with the exposure at 300 Hz and 1.5 mT. The decrease of at least 20% in CFU value was obtained for frequencies above 200 Hz and all five studied magnetic flux densities (0.5 mT. 1.0 mT, 1.5 mT, 2.0 mT, and 2.5 mT).ConclusionsIn summary, the growth rate of the irradiated S. aureus bacteria is affected by radiation of particular parameters, thus revealing resonant effects induced by the applied radiation. The decreased CFU values in all irradiated samples compared to control samples (non-exposed) were observed. Findings provide important insight towards selecting the optimal parameters of ELF PEMF for possible treatment of infected tissue and thus, wound healing promotion.

The synergistic effect of rapamycin and a low frequency pulsed electromagnetic field on the genesis of bone marrow mesenchymal stem cells

Objective To study whether Rapamycin and a low frequency pulsed electromagnetic field (LFPEMF) have synergistic effects on osteogenesis.Methods Bone marrow mesenchymal stem cells (BMSCs) were isolated from 4-week-old Sprague-Dawley rats (male,60-80 g) and cultured.The passage three BMSCs were transplanted into six well plates.The wells were divided into a control group in which the cells were cultivated in Dulbecco's modification of Eagle's medium (DMEM),a rapamycin group in which the cells were cultivated in DMEM containing 5 nM rapamycin,an electromagnetic field group in which the cells were cultivated in DMEM in a LFPEMF,and a combined treatment group in which the cells were cultivated in DMEM containing rapamycin in a LFPEMF.Proteins and RNA were extracted and the calcium disposition was stained using alizarin red after 7,14 and 21 days of incubation.Real-time PCR or western blotting was then used to detect any differences in the expression of the RUNX2,BSP,OPN or BMP2 genes.Results After 7 days of incubation the mRNA expression of the early osteogenesis indicator RUNX2 in the rapamycin group was significantly higher than that in the control group,while the expression of RUNX2 in the LFPEMF group did not differ significantly from that among the controls.The mRNA expression of the middle and late osteogenesis indicators BSP and OPN in the LFPEMF and rapamycin groups were significantly higher than in the control group in the middle (14 d) and late (21 d) periods,but the combined treatment group showed a much weaker effect than in the LFPEMF and rapamycin groups,as shown by significantly lower expression of BSP and OPN.Conclusions A LFPEMF does not have an obvious osteogenic effect in the early stimulating period,but is effective in the middle and late periods.LFPEMFs have no synergistic effect with rapamycin on osteogenesis. Key words: Rapamycin; Osteogenesis; Osteogenesis inducers; Electromagnetic fields

Low Frequency Pulsed Electromagnetic Field Affects Proliferation, Tissue-Specific Gene Expression, and Cytokines Release of Human Tendon Cells

Low frequency pulsed electromagnetic field (PEMF) has proven to be effective in the modulation of bone and cartilage tissue functional responsiveness, but its effect on tendon tissue and tendon cells (TCs) is still underinvestigated. PEMF treatment (1.5 mT, 75 Hz) was assessed on primary TCs, harvested from semitendinosus and gracilis tendons of eight patients, under different experimental conditions (4, 8, 12 h). Quantitative PCR analyses were conducted to identify the possible effect of PEMF on tendon-specific gene transcription (scleraxis, SCX and type I collagen, COL1A1); the release of pro- and anti-inflammatory cytokines and of vascular endothelial growth factor (VEGF) was also assessed. Our findings show that PEMF exposure is not cytotoxic and is able to stimulate TCs' proliferation. The increase of SCX and COL1A1 in PEMF-treated cells was positively correlated to the treatment length. The release of anti-inflammatory cytokines in TCs treated with PEMF for 8 and 12 h was significantly higher in comparison with untreated cells, while the production of pro-inflammatory cytokines was not affected. A dramatically higher increase of VEGF-A mRNA transcription and of its related protein was observed after PEMF exposure. Our data demonstrated that PEMF positively influence, in a dose-dependent manner, the proliferation, tendon-specific marker expression, and release of anti-inflammatory cytokines and angiogenic factor in a healthy human TCs culture model.

Effects of electromagnetic fields on osteogenesis of human alveolar bone-derived mesenchymal stem cells.

This study was performed to investigate the effects of extremely low frequency pulsed electromagnetic fields (ELF-PEMFs) on the proliferation and differentiation of human alveolar bone-derived mesenchymal stem cells (hABMSCs). Osteogenesis is a complex series of events involving the differentiation of mesenchymal stem cells to generate new bone. In this study, we examined not merely the effect of ELF-PEMFs on cell proliferation, alkaline phosphatase (ALP) activity, and mineralization of the extracellular matrix but vinculin, vimentin, and calmodulin (CaM) expressions in hABMSCs during osteogenic differentiation. Exposure of hABMSCs to ELF-PEMFs increased proliferation by 15% compared to untreated cells at day 5. In addition, exposure to ELF-PEMFs significantly increased ALP expression during the early stages of osteogenesis and substantially enhanced mineralization near the midpoint of osteogenesis within 2 weeks. ELF-PEMFs also increased vinculin, vimentin, and CaM expressions, compared to control. In particular, CaM indicated that ELF-PEMFs significantly altered the expression of osteogenesis-related genes. The results indicated that ELF-PEMFs could enhance early cell proliferation in hABMSCs-mediated osteogenesis and accelerate the osteogenesis.

Short-Term Effects of Extremely Low Frequency Pulsed Electromagnetic Field on Corneas with Alkaline Burns in Rabbits

To investigate the short-term effects of extremely low frequency pulsed electromagnetic fields (ELF-PEMF) on the healing of alkaline-burned corneas in rabbits. Fifty-six alkaline-burned corneas from 56 rabbits were categorized into four groups: ELF-PEMF therapy with 2 mTesla (mT) intensity (ELF 2) for 30 minutes twice daily, ELF-PEMF therapy with 5 mT intensity (ELF 5) for 30 minutes twice daily, medical therapy (MT), and controls. Clinical examination together with digital photography of the corneas was performed on days 0, 2, 7, and 14. After euthanizing the rabbits, affected eyes were evaluated by way of histopathology. Finally the clinical and the histopathologic results of the four groups were compared. None of the cases developed limbal ischemia, symblepharon formation, Descemetocele, or corneal perforation. Although the area of corneal defect in the ELF groups on day 2 was significantly less than the defects in MT, it was not notably different from those on days 7 and 14. Rate of significant corneal neovascularization on days 7 and 14 was not statistically different between the groups. The keratocyte loss in MT was significantly higher than in the ELF groups. Mild stromal scar formation was observed more frequently in ELF-PEMF groups than the control. Short-term ELF-PEMF therapy is a safe, noninvasive, and markedly effective method in healing alkaline-burned corneas, and its therapeutic results are comparable with those of MT.

Changes of ocular signs in children with thyroid diseases after intake of bee bread

The objective of the study was to investigate visual acuity, refractive status and eye proptosis in children with thyroid diseases before and after intake of bee bread. There were done investigations of visual acuity, refraction and eye proptosis in 34 children with thyroid diseases at Eye Clinic of Lithuanian University of Health Sciences Medical Academy (age range from 6 to 17 years). 18 patients used bee bread and there was performed low frequency pulsed electromagnetic field therapy. For 16 subjects electromagnetotherapy alone was performed. The values were statistically analyzed with the pretreatment values after three week course of treatment. In the present study we observed an improvement of visual acuity in children with thyroid diseases who used bee bread and there was performed magnetotherapy in comparison with those who were treated magnetotherapy alone. In our study exophthalmometer values and refraction power were not significant changed in both groups. Data analysis indicated increase in visual acuity for subjects who used bee bread and pulsed electromagnetic field therapy to subjects who did not used bee bread. The data we have found suggest that bee bread and magnetotherapy had an influence on visual acuity in children with thyroid diseases.DOI: http://dx.doi.org/10.5755/j01.ct.61.3.2660

Investigation of the effect of pulsed electromagnetic field on the weight of rats

Purpose: To investigate the effect of electromagnetic fields on weight at the rats. Material and Method: 10 female Wistar Albino rats were exposed to 20 beats/s and 50 Hz frequency pulsed electromagnetic field for 4 hours daily for 60 days in experimental inverstigation laboratory. They were kept at 21±1 C° and free access to water and food. There were a control group consisting of 10 rats. Weights of the rats in both groups were measured before and after sudy. The values obtained from both groups were analyzed statistically. Results: The mean weight of the experiment group was 242,6 gr (SD:22,4) and of the control group was 248,3 gr (SD:18,5). At the end of the 60th day the mean values of the experiment and control groups were 266,5 gr (SD:20,8) and 275,4 gr (SD:23,6) respectively. There was no statistically significant diffeence between the groups before and after study. (p>0.05) Conclusion: 50 Hz frequency and 25 beats/s pulsed electromagnetic field did not cause any change in the weight of rats compared to control group.

In vitro effects of low frequency electromagnetic fields on osteoblast proliferation and maturation in an inflammatory environment

An in vitro model was set up to investigate the effects of low frequency pulsed electromagnetic fields (PEMF) and its induced electric fields on osteoblast cells under inflammatory conditions. Osteoblasts (7F2) were seeded on top of chitosan scaffolds and co-cultured with macrophage cells (RAW 264.7) growing on the bottom of culture wells, stimulated by lipopolysaccharide to release reactive oxygen species including nitric oxide (NO). The co-culture was exposed to PEMF (magnitude of the magnetic field = 1.5 mT; induced electric voltage = 2.5 mV; frequency = 75 Hz; pulse duration = 1.3 ms) for 9 h. The osteoblasts were examined for their proliferation, viability, alkaline phosphatase (ALP) activity, and genetic expressions of type I collagen (COL I) and osteocalcin (OC), immediately and 7 days after PEMF exposure (days 0 and 7). Macrophage cell viability and NO concentration in the medium were monitored before and after PEMF exposure. The PEMF-exposed co-culture released a significantly higher amount of NO (65 µM) compared to control (17 µM) on day 7. Despite the high level of NO in the medium that was reported to be cytotoxic, PEMF-exposed osteoblasts had enhanced cell proliferation (23%), viability (36%), and COL I mRNA expression (3.4-fold) compared to the controls. The osteoblasts subjected to the PEMF had 41% less ALP activity than the control, which was associated with the active cell proliferation and COL I expression. The expression of OC mRNA was not seen in either the PEMF or control group, indicating cells had not entered the mineralization stage by day 7.