The cellular effects of Pulsed Electromagnetic Fields on osteoblasts: A review

Culturing 3D chitosan/gelatin/nano-hydroxyapatite and bone-derived scaffolds in a dynamic environment enhances osteochondral reconstruction

Bioreactor can provide a dynamic culture environment for the in vitro construction of osteochondral tissue engineering. They facilitate more efficient exchange of nutrients and provide mechanical and other beneficial stimulation. Previous findings demonstrated that rotary flask (RF) bioreactor, rotary cell culture system (RCCS), or electromagnetic field (EMF) mediated scaffold culture could create a favorable dynamic environment for osteochondral tissue engineering. However, it is still unclear whether there is an optimal bioreactor or if bioreactors under multi-parameter coupling conditions are conducive to osteochondral tissue engineering. Based on this, the application of static T-flask (TF), RF, RCCS, and coupling environment of RCCS and EMF for osteochondral tissue engineering were systematically compared. The results showed that the RCCS/EMF culture system achieved the highest level of cellular proliferation and directed differentiation. Compared with the static culture group, the expression levels of chondrogenic factors of Sox9, Col II, and ACAN and osteogenic factors of Runx2, OCN, and Col I in RCCS/EMF culture system were 2.90 ± 0.10, 3.53 ± 0.05, 3.15 ± 0.08, 7.16 ± 0.15, 5.01 ± 0.21 and 3.99 ± 0.17 folds, respectively. The 'Active osteochondral' constructs (The construct is composed of chitosan/gelatin/nano-hydroxyapatite and bone-derived scaffolds) were prepared under different culture modes in vitro and implanted into the femoral condylar defect of New Zealand rabbits. After 12 weeks, all culture modes could effectively promote the repair of osteochondral defects, in which the RCCS/EMF intervention had the best effect on the in vivo in-situ repair of osteochondral tissues. Furthermore, the fabricated cartilage and subchondral bone in the RCCS/EMF treatment group were most similar to the surrounding natural tissues, providing a new therapeutic idea for osteochondral tissue engineering.

Personal exposure to radiofrequency electromagnetic fields: A comparative analysis of international, national, and regional guidelines

A worldwide overview and analysis for the existing limits of human exposure to Radiofrequency Electromagnetic Fields (RF-EMF) is given in this paper. These reference levels have been established by different national and even regional governments, which can be based on the guidelines provided by the recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP), the International Committee on Electromagnetic Safety of the Institute of Electrical and Electronics Engineers (IEEE), and even in the United States of the Federal Communications Commission (FCC), as well as, are based on the so-called precautionary principle. Explicit reference is made to the exposure limits adopted in countries or regions, such as Canada, Italy, Poland, Switzerland, China, Russia, France, and regions of Belgium (Brussels, Flanders, Wallonia), where the limits are much lower than the international standards. The limits are compared to a selected set of in-situ measurements. This clearly shows that the measured values are typically very small compared to the international standards but could be somewhat higher compared to the reduced limits. Based on this observation and the reasonable assumption that the sensitivity of people to Electromagnetic Fields (EMF) is the same everywhere (whole-body), we propose the idea to establish a worldwide reference limit for the general public, thus applicable in all countries, if the ICNIRP considers it appropriate. Research must continue to generate measurement data that demonstrate the levels of exposure to which we are really exposed, and with this, provide arguments to the organizations that established the guidelines, especially the ICNIRP, to evaluate whether the current limits are too much. High and can be modified when considered pertinent. To the best of our knowledge, at no time has the reference level for the general public been exceeded.

Human osteosarcoma cells in response to ELF-MF: Morphological remodeling compared to cell proliferation

Purpose

The present study aimed to assess the effects of extremely low-frequency electromagnetic fields (ELF-MF) on structural changes of human osteosarcoma cells by analyzing the stained cytoskeleton for assessing the relationship between the fractal dimension parameter and proliferation rate of radiation-induced cells.

Materials and Methods

In this study, 2-mT magnetic fields with various waveforms, including sinusoidal, triangular, and pulsed shapes, were employed to determine the biological effects of ELF-EMF on the human osteosarcoma MG-63 cell line. All experiments were performed in two modes: continuous exposure at 3 h and fractionated irradiations at 3 consecutive days. Afterward, the proliferation assay was implemented for assessing the cell proliferation in each group. Moreover, immunofluorescence staining and confocal imaging were performed to determine the cell shape index. Furthermore, fractal dimension analysis was carried out by processing morphological images.

Results

The proliferation and shape index parameters of radiation-induced osteosarcomas significantly decreased compared with non-irradiated cells. In addition, fractal dimensions significantly increased following fractionated exposure at 3 consecutive days.

Conclusions

Assessing the fractal dimensions can be considered as a new morphological index for the prognosis of the structural remodeling of human osteosarcoma cells in response to fractionated irradiation of ELF-MF. In addition, various waveforms induce a similar effect on morphological remodeling and cell proliferation.

Measurement studies of personal exposure to radiofrequency electromagnetic fields: A systematic review

The last 25 years have seen an increase in the number of radiofrequency sources with the global adoption of smartphones as primary connectivity devices. The objective of this work was to review and evaluate the measured studies of personal exposure to Radiofrequency Electromagnetic Fields (RF-RMF) and meet the basic quality criteria eligible for inclusion in this Review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, following the eligibility criteria of the PECO (Population, Exposure, Comparator, and Outcome) methodology, and the instrument for critical reading Critical Appraisal Skills Programme Español (CASPe). We systematically reviewed the works published between January 1, 1998, and December 31, 2021, yielding 56 publications. Of the different types of studies in which personal exposure to RF-EMF has been measured with two measurement methodologies can be highlighted: Personal measurements with volunteers and Personal measurements with a trained researcher (touring a specific area, one or several microenvironments, an entire city, walking or in some means of transport). Personal exposimeters were used in 83% of the studies. The lowest mean was measured in Egypt with a value of 0.00100 μW/m² (1.00 nW/m²) in 2007 and the highest mean was measured in Belgium with a value of 285000 μW/m² (0.285 W/m²) in 2019. The results of our study confirm that RF-EMF exposure levels are well below the maximum levels established by the ICNIRP guidelines.

Pulsed electromagnetic field attenuates bone fragility in estrogen-deficient osteoporosis in rats

BACKGROUND

The pulsed electromagnetic fields (PEMFs) seem effective in increasing bone mineral density and promoting osteogenesis and bone healing.

OBJECTIVE

To examine the effect of two different modalities of PEMFs therapy in comparison with the recommended pharmacological treatment on experimental osteoporosis in rats.

METHODS

The experimental model of estrogen-deficient osteoporosis induced by ovariectomy was used in this study. The animals were exposed to PEMFs of various frequencies (40 Hz and 25 Hzk), intensities (10 mT and 36.4 μT), lengths of exposure, and the effects were compared with the standard treatment with pamidronate, vitamin D, and calcium supplementation.

RESULTS

The application of PEMF40Hz, significantly reduced the osteoporotic bone loss in female rats that were confirmed with biochemical, biomechanical, and histological analyses. These effects were more pronounced than in osteoporotic animals treated with pamidronate, vitamin D, and calcium supplementation. On the contrary, the exposure to PEMF25Hz did not show restorative effects but led to further progression of osteoporosis.

CONCLUSION

The exposure to PEMF40Hz, significantly restored osteoporosis and attenuated bone fragility in comparison to the rats exposed to PEMF25Hz or those treated with pamidronate, vitamin D, and calcium supplementation.

Effects of Magnetic Stimulation on Dental Implant Osseointegration: A Scoping Review

This PRISMA-ScR driven scoping review aims to evaluate the influence of magnetic field stimulation on dental implant osseointegration. Seven databases were screened adopting ad-hoc strings. All clinical and preclinical studies analyzing the effects of magnetic fields on dental implant osseointegration were included. From 3124 initial items, on the basis of the eligibility criteria, 33 articles, regarding both Pulsed ElectroMagnetic Fields (PEMF) and Static magnetic Fields from permanent Magnets (SFM) were finally included and critically analyzed. In vitro studies showed a positive effect of PEMF, but contrasting effects of SFM on bone cell proliferation, whereas cell adhesion and osteogenic differentiation were induced by both types of stimulation. In vivo studies showed an increased bone-to-implant contact rate in different animal models and clinical studies revealed positive effects on implant stability, under magnetic stimulation. In conclusion, although positive effects of magnetic exposure on osteogenesis activity and osseointegration emerged, this scoping review highlighted the need for further preclinical and clinical studies. More standardized designs, accurate choice of stimulation parameters, adequate methods of evaluation of the outcomes, greater sample size and longer follow-ups are needed to clearly assess the effect of magnetic fields on dental implant osseointegration.

Bioengineered Living Bone Grafts-A Concise Review on Bioreactors and Production Techniques In Vitro

It has been observed that bone fractures carry a risk of high mortality and morbidity. The deployment of a proper bone healing method is essential to achieve the desired success. Over the years, bone tissue engineering (BTE) has appeared to be a very promising approach aimed at restoring bone defects. The main role of the BTE is to apply new, efficient, and functional bone regeneration therapy via a combination of bone scaffolds with cells and/or healing promotive factors (e.g., growth factors and bioactive agents). The modern approach involves also the production of living bone grafts in vitro by long-term culture of cell-seeded biomaterials, often with the use of bioreactors. This review presents the most recent findings concerning biomaterials, cells, and techniques used for the production of living bone grafts under in vitro conditions. Particular attention has been given to features of known bioreactor systems currently used in BTE: perfusion bioreactors, rotating bioreactors, and spinner flask bioreactors. Although bioreactor systems are still characterized by some limitations, they are excellent platforms to form bioengineered living bone grafts in vitro for bone fracture regeneration. Moreover, the review article also describes the types of biomaterials and sources of cells that can be used in BTE as well as the role of three-dimensional bioprinting and pulsed electromagnetic fields in both bone healing and BTE.

Osteogenesis Modulation: Induction of Mandibular Bone Growth in Adults by Electrical Field for Aesthetic Purposes

BACKGROUND

A new technique in plastic surgery termed Osteogenesis Modulation is described. This technique uses a surgically implanted, battery-operated medical device to deliver customized electrical pulses to produce mandibular bone growth. This device was designed to be a temporary, nonpermanent implant. The purpose of this study was to review both the safety and efficacy of Osteogenesis Modulation.

METHODS

This study comprises two phases. Phase I involved experimental technology development and animal experiments. Phase II included technology development for clinical use and a clinical trial. In Phase II, four patients with a diagnosis of mandibular hypoplasia and microgenia underwent surgical implantation of the novel medical device over the chin bone. Once a satisfactory change of contour of mandibular bone was achieved, the devices were removed. In all patients, the devices were left in place for 12 months, then surgically removed under local anesthesia. Preoperative and long-term postoperative cephalometric controls were done.

RESULTS

In all patients, symmetrical mandibular bone growth was observed with good-to-excellent aesthetic results. The overall follow-up period was 39 months. Cephalometric controls taken 3 to 6 months after the device removal showed an average increase in mandible length of 5.26mm (range, 2.83-7.60mm) CONCLUSIONS: Preliminary clinical results suggest that Osteogenesis Modulation is a safe, minimally invasive, and effective alternative treatment for the correction of mandibular hypoplasia in selected cases.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of electromagnetic radiation on the liver structure and ultrastructure of in utero irradiated rats

The aim of this study was to observe the influence of electromagnetic radiation (EMR) on the structure and ultrastructure of the rat’s liver. The pregnant rats used in the experiment were exposed to a pulsed microwave radiation (frequency of 2.45 GHz; mean power density of 2.8 mW/cm2) daily for 2 h, throughout their pregnancy. After delivery, the offspring was not exposed to EMR. Samples of the liver of 5-week-old offspring were subjected to histopathological evaluation. They were processed for light and transmission electron microscopy. Our results indicated that EMR did not cause pronounced changes in the structure of the liver of the investigated offspring. The size and shape of liver lobuli was preserved and the amount of connective tissue in the liver parenchyma did not increase. However, electron microscopy revealed changes in the shape and number of microvilli at the vascular pole of hepatocytes, and formation of vesicles of various shapes and sizes. The endothelial cells were swollen with larger fenestrations compared to the control group. The spaces of Disse were irregular and dilated. Even though these changes were only mild, further studies are needed to determine the effect of EMR and clarify its potential risk during pregnancy.

Complex Electromagnetic Fields Reduce Candida albicans Planktonic Growth and Its Adhesion to Titanium Surfaces

This study evaluates the effects of different programs of complex electromagnetic fields (C.M.F.s) on Candida albicans, in planktonic and sessile phase and on human gingival fibroblasts (HGF cells). In vitro cultures of C. albicans ATCC 10231 and HGF cells were exposed to different cycles of C.M.F.s defined as: oxidative stress, oxidative stress/antibacterial, antibacterial, antibacterial/oxidative stress. Colony forming units (CFUs), metabolic activity, cells viability (live/dead), cell morphology, filamentation analysis, and cytotoxicity assay were performed. The broth cultures, exposed to the different C.M.F.s, were grown on titanium discs for 48 h. The quantity comparisons of adhered C. albicans on surfaces were determined by CFUs and scanning electron microscopy. The C. albicans growth could be readily controlled with C.M.F.s reducing the number of cultivable planktonic cells vs. controls, independently by the treatment applied. In particular, the antibacterial program was associated with lower levels of CFUs. The quantification of the metabolic activity was significantly lower by using the oxidative stress program. Live/dead images showed that C.M.F.s significantly decreased the viability of C. albicans. C.M.F.s inhibited C. albicans virulence traits reducing hyphal morphogenesis, adhesion, and biofilm formation on titanium discs. The MTS assay showed no negative effects on the viability of HGF. Independent of the adopted protocol, C.M.F.s exert antifungal and anti-virulence action against C. albicans, no cytotoxicity effects on HGF and can be useful in the prevention and treatment of yeast biofilm infections.

Pulsed electromagnetic fields improve the healing process of Achilles tendinopathy: a pilot study in a rat model

Aims

In the context of tendon degenerative disorders, the need for innovative conservative treatments that can improve the intrinsic healing potential of tendon tissue is progressively increasing. In this study, the role of pulsed electromagnetic fields (PEMFs) in improving the tendon healing process was evaluated in a rat model of collagenase-induced Achilles tendinopathy.

Methods

A total of 68 Sprague Dawley rats received a single injection of type I collagenase in Achilles tendons to induce the tendinopathy and then were daily exposed to PEMFs (1.5 mT and 75 Hz) for up to 14 days - starting 1, 7, or 15 days after the injection - to identify the best treatment option with respect to the phase of the disease. Then, 7 and 14 days of PEMF exposure were compared to identify the most effective protocol.

Results

The daily exposure to PEMFs generally provided an improvement in the fibre organization, a decrease in cell density, vascularity, and fat deposition, and a restoration of the physiological cell morphology compared to untreated tendons. These improvements were more evident when the tendons were exposed to PEMFs during the mid-acute phase of the pathology (7 days after induction) rather than during the early (1 day after induction) or the late acute phase (15 days after induction). Moreover, the exposure to PEMFs for 14 days during the mid-acute phase was more effective than for 7 days.

Conclusion

PEMFs exerted a positive role in the tendon healing process, thus representing a promising conservative treatment for tendinopathy, although further investigations regarding the clinical evaluation are needed.

Cite this article: Bone Joint Res 2020;9(9):613–622.

Role of pulsed electromagnetic fields after joint replacements

Although the rate of patients reporting satisfaction is generally high after joint replacement surgery, up to 23% after total hip replacement and 34% after total knee arthroplasty of treated subjects report discomfort or pain 1 year after surgery. Moreover, chronic or subacute inflammation is reported in some cases even a long time after surgery. Another open and debated issue in prosthetic surgery is implant survivorship, especially when related to good prosthesis bone ingrowth. Pulsed Electro Magnetic Fields (PEMFs) treatment, although initially recommended after total joint replacement to promote bone ingrowth and to reduce inflammation and pain, is not currently part of usual clinical practice. The purpose of this review was to analyze existing literature on PEMFs effects in joint replacement surgery and to report results of clinical studies and current indications. We selected all currently available prospective studies or RCT on the use of PEMFs in total joint replacement with the purpose of investigating effects of PEMFs on recovery, pain relief and patients’ satisfaction following hip, knee or shoulder arthroplasty. All the studies analyzed reported no adverse effects, and good patient compliance to the treatment. The available literature shows that early control of joint inflammation process in the first days after surgery through the use of PEMFs should be considered an effective completion of the surgical procedure to improve the patient’s functional recovery.

Translational Insights into Extremely Low Frequency Pulsed Electromagnetic Fields (ELF-PEMFs) for Bone Regeneration after Trauma and Orthopedic Surgery

The finding that alterations in electrical potential play an important role in the mechanical stimulation of the bone provoked hype that noninvasive extremely low frequency pulsed electromagnetic fields (ELF-PEMF) can be used to support healing of bone and osteochondral defects. This resulted in the development of many ELF-PEMF devices for clinical use. Due to the resulting diversity of the ELF-PEMF characteristics regarding treatment regimen, and reported results, exposure to ELF-PEMFs is generally not among the guidelines to treat bone and osteochondral defects. Notwithstanding, here we show that there is strong evidence for ELF-PEMF treatment. We give a short, confined overview of in vitro studies investigating effects of ELF-PEMF treatment on bone cells, highlighting likely mechanisms. Subsequently, we summarize prospective and blinded studies, investigating the effect of ELF-PEMF treatment on acute bone fractures and bone fracture non-unions, osteotomies, spinal fusion, osteoporosis, and osteoarthritis. Although these studies favor the use of ELF-PEMF treatment, they likewise demonstrate the need for more defined and better controlled/monitored treatment modalities. However, to establish indication-oriented treatment regimen, profound knowledge of the underlying mechanisms in the sense of cellular pathways/events triggered is required, highlighting the need for more systematic studies to unravel optimal treatment conditions.

DNA-Related Modifications in a Mixture of Human Lympho-Monocyte Exposed to Radiofrequency Fields and Detected by Raman Microspectroscopy Analysis

Human exposure to electromagnetic fields (EMFs) has risen considerably during the last decades, because of the industrial and technical development and the consequent increase of artificial EMFs sources. In particular, blood is largely involved in the environmental EMF exposure, because it is located everywhere in the human body. Lympho-monocyte cells are blood components that protect the human organism against infections. In this study, we investigate biochemical changes in lympho-monocyte cells extracted from human peripheral blood after exposure to EMFs at 1.8 GHz frequency and 200 V/m electric field strength for times ranging from 5 to 20 h inside a reverberation chamber. Some mixtures of cells, coming from many human subjects, were exposed and successively investigated by means of Raman micro-spectroscopy technique and principal components analysis. The spectral analysis was able to detect variations of the biochemical composition of the nucleus of exposed cells. Such modifications are mainly detectable as an intensity decrease of some DNA and nucleic acid Raman peaks with respect to the intensity of some protein peaks and they were most evident in the case of 20 h exposed samples. These results were in agreement with the increase of reactive oxygen species (ROS) production, observed in the exposed cells. Overall, the obtained results point out that EMFs exposure may induce modifications of the DNA in some blood cells of long-term exposed people.

The Response of Osteoblasts and Bone to Sinusoidal Electromagnetic Fields: Insights from the Literature

Electromagnetic fields (EMFs) have been proposed as a tool to ameliorate bone formation and healing. Despite their promising results, however, they have failed to enter routine clinical protocols to treat bone conditions where higher bone mass has to be achieved. This is no doubt also due to a fundamental lack of knowledge and understanding on their effects and the optimal settings for attaining the desired therapeutic effects. This review analysed the available in vitro and in vivo studies that assessed the effects of sinusoidal EMFs (SEMFs) on bone and bone cells, comparing the results and investigating possible mechanisms of action by which SEMFs interact with tissues and cells. The effects of SEMFs on bone have not been as thoroughly investigated as pulsed EMFs; however, abundant evidence shows that SEMFs affect the proliferation and differentiation of osteoblastic cells, acting on multiple cellular mechanisms. SEMFs have also proven to increase bone mass in rodents under normal conditions and in osteoporotic animals.