The effect of pulsed electromagnetic fields and dehydroepiandrosterone on viability and osteo-induction of human mesenchymal stem cells

Evaluation of Methenolone Enanthate Efficacy in Preventing MRONJ: A Randomized Trial on Rats

BACKGROUND

It is well-known that oral surgical procedures pose a high risk for medication-related osteonecrosis of the jaw in patients taking bisphosphonates. Although some position papers and guidelines have been published with regard to its treatment, few studies have investigated prevention methods. This study investigates the effectiveness of methenolone enanthate, an anabolic steroid, for the prevention of medication-related osteonecrosis of the jaw.

METHODS

Thirty-six Wistar rats were divided into three groups. Two experimental groups, Z and ZM, took zoledronic acid for 6 weeks prior to extraction of the left maxillary first molar. The Group ZM also was given methenolone enanthate continuously for 1 week before and 4 weeks after the extraction. The control group was not given any medication. The rats were euthanized 5 weeks after extraction. The extraction socket was evaluated clinically for bone exposure and histologically for inflammation, hyperemia, collagen fibers, epithelialization, number of osteoclasts, and empty lacunae.

RESULTS

Six rats died during the experimental research. The bone exposure rate, mean numbers of attached osteoclasts (in 40× magnification), and empty lacunae (in 100× magnification) were 0%, 4%, and 0.8% in Group C; 75%, 1%, and 8% in Group Z; and 10%, 2.1%, and 3% in Group ZM, respectively. Significant differences exist between all groups regarding the number of empty lacunae. There were significant differences between Group C/ZM and Group Z in terms of bone exposure rate, inflammation, hyperemia, collagen fiber organization, and epithelialization.

CONCLUSION

In our tested preclinical model, methenolone enanthate has shown potential for preventing medication-related osteonecrosis of the jaw.

Unraveling the transcriptome profile of pulsed electromagnetic field stimulation in bone regeneration using a bioreactor-based investigation platform

INTRODUCTION

Human mesenchymal stem cells (hMSCs) sense and respond to biomechanical and biophysical stimuli, yet the involved signaling pathways are not fully identified. The clinical application of biophysical stimulation including pulsed electromagnetic field (PEMF) has gained momentum in musculoskeletal disorders and bone tissue engineering.

METHODOLOGY

We herein aim to explore the role of PEMF stimulation in bone regeneration by developing trabecular bone-like tissues, and then, culturing them under bone-like mechanical stimulation in an automated perfusion bioreactor combined with a custom-made PEMF stimulator. After selecting the optimal cell seeding and culture conditions for inspecting the effects of PEMF on hMSCs, transcriptomic studies were performed on cells cultured under direct perfusion with and without PEMF stimulation.

RESULTS

We were able to identify a set of signaling pathways and upstream regulators associated with PEMF stimulation and to distinguish those linked to bone regeneration. Our findings suggest that PEMF induces the immune potential of hMSCs by activating and inhibiting various immune-related pathways, such as macrophage classical activation and MSP-RON signaling in macrophages, respectively, while promoting angiogenesis and osteogenesis, which mimics the dynamic interplay of biological processes during bone healing.

CONCLUSIONS

Overall, the adopted bioreactor-based investigation platform can be used to investigate the impact of PEMF stimulation on bone regeneration.

The Effect of Different Frequencies of Pulsed Electromagnetic Fields on Cartilage Repair of Adipose Mesenchymal Stem Cell-Derived Exosomes in Osteoarthritis

BACKGROUND

The intra-articular injection of mesenchymal stem cell (MSC)-derived exosomes has already been proved to reverse osteoarthritic cartilage degeneration. Pulsed electromagnetic field (PEMF) has been found to regulate the biogenic function of MSCs. However, the effect of PEMF on MSC-derived exosomes has not yet been characterized. The aim of this study was to elucidate the regulatory role of different frequencies of PEMF in promoting the osteoarthritic cartilage regeneration of MSC-derived exosomes.

METHODS

The adipose tissue-derived MSCs (AMSCs) were extracted from the epididymal fat of healthy rats and further exposed to the PEMF at 1 mT amplitude and a frequency of 15, 45, and 75 Hz, respectively, in an incubator. The chondrocytes were treated with interlukin-1β (IL-1β) and the regenerative effect of co-culturing with PEMF-exposed AMSC-derived exosomes was assessed via Western blot, quantitative polymerase chain reaction, and ELISA assays. A rat model of osteoarthritis was established by anterior cruciate ligament transection (ACLT) surgery and received 4 times intra-articular injection of PEMF-exposed AMSC-derived exosomes once a week. After 8 weeks, the knee joint specimens of rats were collected for micro-computed tomography and histologic analyses.

RESULTS

PEMF-exposed AMSC-derived exosomes could be endocytosed with IL-1β-induced chondrocytes. Compared with the AMSC-derived exosomes alone, the PEMF-exposed AMSC-derived exosomes substantially suppressed the inflammation and extracellular matrix degeneration of IL-1β-induced chondrocytes as shown by higher expression of transcripts and proteins of COL2A1, SOX9, and ACAN and lower expression of MMP13 and caspase-1. Of these, the 75-Hz PEMF presented a more significant inhibitive effect than the 15-Hz and 45-Hz PEMFs. Furthermore, the intra-articular injection of 75-Hz PEMF-exposed exosomes could obviously increase the number of tibial epiphyseal trabeculae, lead to a remarkable decrease in Osteoarthritis Research Society International score, and upregulate the COL2A1 and ACAN protein level of the degenerated cartilage.

CONCLUSION

The present study demonstrated that PEMF stimulation could effectively promote the regeneration effects of AMSC-derived exosomes on osteoarthritic cartilage. Compared with other frequency parameters, the PEMF at a frequency of 75 Hz showed a superior positive effect on AMSC-derived exosomes in suppressing the IL-1β-induced chondrocyte inflammation and extracellular matrix catabolism, as well as the osteoarthritic cartilage degeneration.

Cell-cell interactions and fluctuations in the direction of motility promote directed migration of osteoblasts in direct current electrotaxis

Under both physiological (development, regeneration) and pathological conditions (cancer metastasis), cells migrate while sensing environmental cues in the form of mechanical, chemical or electrical stimuli. In the case of bone tissue, osteoblast migration is essential in bone regeneration. Although it is known that osteoblasts respond to exogenous electric fields, the underlying mechanism of electrotactic collective movement of human osteoblasts is unclear. Here, we present a computational model that describes the osteoblast cell migration in a direct current electric field as the motion of a collection of active self-propelled particles and takes into account fluctuations in the direction of single-cell migration, finite-range cell-cell interactions, and the interaction of a cell with the external electric field. By comparing this model with in vitro experiments in which human primary osteoblasts are exposed to a direct current electric field of different field strengths, we show that cell-cell interactions and fluctuations in the migration direction promote anode-directed collective migration of osteoblasts.

Evaluation of Pulsed Electromagnetic Field Effects: A Systematic Review and Meta-Analysis on Highlights of Two Decades of Research In Vitro Studies

Pulsed electromagnetic field (PEMF) therapy is a type of physical stimulation that affects biological systems by producing interfering or coherent fields. Given that cell types are significantly distinct, which represents an important factor in stimulation, and that PEMFs can have different effects in terms of frequency and intensity, time of exposure, and waveform. This study is aimed at investigating if distinct positive and negative responses would correspond to specific characteristics of cells, frequency and flux density, time of exposure, and waveform. Necessary data were abstracted from the experimental observations of cell-based in vitro models. The observations were obtained from 92 publications between the years 1999 and 2019, which are available on PubMed and Web of Science databases. From each of the included studies, type of cells, pulse frequency of exposure, exposure flux density, and assayed cell responses were extracted. According to the obtained data, most of the experiments were carried out on human cells, and out of 2421 human cell experiments, cell changes were observed only in 51.05% of the data. In addition, the results pointed out the potential effects of PEMFs on some human cell types such as MG-63 human osteosarcoma cells (p value < 0.001) and bone marrow mesenchymal stem cells. However, human osteogenic sarcoma SaOS-2 (p < 0.001) and human adipose-derived mesenchymal stem cells (AD-MSCs) showed less sensitivity to PEMFs. Nevertheless, the evidence suggests that frequencies higher than 100 Hz, flux densities between 1 and 10 mT, and chronic exposure more than 10 days would be more effective in establishing a cellular response. This study successfully reported useful information about the role of cell type and signal characteristic parameters, which were of high importance for targeted therapies using PEMFs. Our findings would provide a deeper understanding about the effect of PEMFs in vitro, which could be useful as a reference for many in vivo experiments or preclinical trials.

Synergistic Effect of PVDF-Coated PCL-TCP Scaffolds and Pulsed Electromagnetic Field on Osteogenesis

Bone exhibits piezoelectric properties. Thus, electrical stimulations such as pulsed electromagnetic fields (PEMFs) and stimuli-responsive piezoelectric properties of scaffolds have been investigated separately to evaluate their efficacy in supporting osteogenesis. However, current understanding of cells responding under the combined influence of PEMF and piezoelectric properties in scaffolds is still lacking. Therefore, in this study, we fabricated piezoelectric scaffolds by functionalization of polycaprolactone-tricalcium phosphate (PCL-TCP) films with a polyvinylidene fluoride (PVDF) coating that is self-polarized by a modified breath-figure technique. The osteoinductive properties of these PVDF-coated PCL-TCP films on MC3T3-E1 cells were studied under the stimulation of PEMF. Piezoelectric and ferroelectric characterization demonstrated that scaffolds with piezoelectric coefficient d33 = -1.2 pC/N were obtained at a powder dissolution temperature of 100 °C and coating relative humidity (RH) of 56%. DNA quantification showed that cell proliferation was significantly enhanced by PEMF as low as 0.6 mT and 50 Hz. Hydroxyapatite staining showed that cell mineralization was significantly enhanced by incorporation of PVDF coating. Gene expression study showed that the combination of PEMF and PVDF coating promoted late osteogenic gene expression marker most significantly. Collectively, our results suggest that the synergistic effects of PEMF and piezoelectric scaffolds on osteogenesis provide a promising alternative strategy for electrically augmented osteoinduction. The piezoelectric response of PVDF by PEMF, which could provide mechanical strain, is particularly interesting as it could deliver local mechanical stimulation to osteogenic cells using PEMF.

Synergic effects of extremely low-frequency electromagnetic field and betaine on in vitro osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells

Human adipose tissue-derived mesenchymal stem cells (hADSCs) due to easy extraction, relative abundance, in vitro expansion and differentiation potential, frozen storage capability, and ability to secrete cytokines, compared to other stem cells, are appropriate candidate in regenerative medicine. Extremely low-frequency electromagnetic fields (ELF-EMF) and betaine are two safe factors in bone lesions repair. This study was designed to assess the osteogenic differentiation potential of these factors on hADSCs. The samples were collected from women undergoing liposuction after obtaining written consent. The hADSCs were extracted and treated with osteogenesis differentiation medium (OD) as the positive control, with OD and betaine (BET group), with OD and EMF (EMF group), and with OD and betaine and EMF (BET+EMF group) for 21 d; the negative control consisted of cells without treatment. Betaine 10 mM and EMF with 50-Hz frequency, 1-mT intensity (8 h daily), and in the form of sinus wave were used. Osteogenic differentiation was evaluated by Alizarin Red staining, alkaline phosphatase activity, calcium deposition, and real-time PCR. A significant increase in calcium deposition in the BET+EMF group was observed compared to the other groups. The activity of alkaline phosphatase in the positive control and BET groups was increased significantly compared to EMF and BET + EMF groups and a significant increase of this enzyme activity in the BET + EMF compared to EMF group was observed. The expression of RUNX2 and OCN genes in the EMF-treated groups were significantly reduced compared to the non-EMF-treated groups, and BET+EMF showed a significant increase of RUNX2 gene expression as compared the EMF group. The ELF-EMF leads to a decrease in the osteogenic differentiation and the expression RUNX2 and OCN genes in hADSCs. But osteogenic differentiation and RUNX2 gene expression were increased post-induction by betaine. The synergic effect of betaine and EMF on the osteogenic differentiation and related genes expression of hADSCs was higher than EMF.

Evaluation of pulsed electromagnetic field protocols in implant osseointegration: in vivo and in vitro study

OBJECTIVES

The present study aims to evaluate two protocols of pulsed electromagnetic field (PEMF) on osseointegration and establish one that addresses ideal parameters for its use in dentistry, especially in the optimization of the implants osseointegration process.

MATERIALS AND METHODS

Sixty male rats (Wistar) were allocated into three experimental groups: control (GC), test A (GTA, 3 h exposed), and test B (GTB, 1 h exposed). All animals received titanium implants in both tibias, and PEMF application (15 Hz, ± 1 mT, 5 days/week) occurred only in the test groups. They were euthanized at 03, 07, 21, and 45 days after PEMF therapy. Removal torque, histomorphometric measurements, three-dimensional radiographic evaluation, and in vitro biological assay analyses were performed.

RESULTS

GTB showed better results compared with GTA in removal torque tests, in bone volume and bone mineral density, cell viability, total protein content, and mineralization nodules (p < 0.05). GTA showed better performance in trabecular bone thickness and cell proliferation compared with GTB (p < 0.05), especially at osseointegration early periods. In the histomorphometric analysis and number of trabeculae, there were no differences in the test groups.

CONCLUSION

PEMF as a biostimulator was effective in optimizing the events in bone tissue that lead to osseointegration, especially when applied for a shorter time and in the initial periods of bone healing.

CLINICAL RELEVANCE

The PEMF therapy is an effective alternative method for optimizing bone healing.

DHEA in bone: the role in osteoporosis and fracture healing

Dehydroepiandrosterone (DHEA) is a metabolic intermediate in the biosynthesis of estrogens and androgens with a past clouded in controversy and bold claims. It was once touted as a wonder drug, a fountain of youth that could cure all ailments. However, in the 1980s DHEA was banned by the FDA given a lack of documented health benefits and long-term use data. DHEA had a revival in 1994 when it was released for open market sale as a nutritional supplement under the Dietary Supplement Health and Safety Act. Since that time, there has been encouraging research on the hormone, including randomized controlled trials and subsequent meta-analyses on various conditions that DHEA may benefit. Bone health has been of particular interest, as many of the metabolites of DHEA are known to be involved in bone homeostasis, specifically estrogen and testosterone. Studies demonstrate a significant association between DHEA and increased bone mineral density, likely due to DHEA's ability to increase osteoblast activity and insulin like growth factor 1 (IGF-1) expression. Interestingly, IGF-1 is also known to improve fracture healing, though DHEA, a potent stimulator of IGF-1, has never been tested in this scenario. The aim of this review is to discuss the history and mechanisms of DHEA as they relate to the skeletal system, and to evaluate if DHEA has any role in treating fractures.

Human Osteoblast Migration in DC Electrical Fields Depends on Store Operated Ca2+-Release and Is Correlated to Upregulation of Stretch-Activated TRPM7 Channels

Fracture healing and bone regeneration, particularly in the elderly, remains a challenge. There is an ongoing search for methods to activate osteoblasts, and the application of electrical fields is an attractive approach in this context. Although it is known that such electromagnetic fields lead to osteoblast migration and foster mesenchymal osteogenic differentiation, so far the mechanisms of osteoblast activation remain unclear. Possible mechanisms could rely on changes in Ca²⁺-influx via ion channels, as these are known to modulate osteoblast activity, e.g., via voltage-sensitive, stretch-sensitive, transient-receptor-potential (TRP) channels, or store-operated release. In the present in vitro study, we explored whether electrical fields are able to modulate the expression of voltage-sensitive calcium channels as well as TRP channels in primary human osteoblast cell lines. We show migration speed is significantly increased in stimulated osteoblasts (6.4 ± 2.1 μm/h stimulated, 3.6 ± 1.1 μm/h control), and directed toward the anode. However, within a range of 154–445 V/m, field strength did not correlate with migration velocity. Neither was there a correlation between electric field and voltage-gated calcium channel (Ca_v3.2 and Ca_v1.4) expression. However, the expression of TRPM7 significantly correlated positively to electric field strength. TRPM7 channel blockade using NS8593, in turn, did not significantly alter migration speed, nor did blockade of Ca_v3.2 and Ca_v1.4 channels using Ni⁺ or verapamil, respectively, while a general Ca²⁺-influx block using Mg²⁺ accelerated migration. Stimulating store-operated Ca²⁺-release significantly reduced migration speed, while blocking IP3 had only a minor effect (at low and high concentrations of 2-APB, respectively). We conclude that (i) store operated channels negatively modulate migration speed and that (ii) the upregulation of TRPM7 might constitute a compensatory mechanism-which might explain how increasing expression levels at increasing field strengths result in constant migration speeds.

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.

Conductive nanostructured Si biomaterials enhance osteogeneration through electrical stimulation

It is well known that the differentiation of stem cells is affected by the cell culture medium, the scaffold surface and electrochemical signals. However, stimulation of patterned biomaterials seeded with stem cell cultures has not been explored. Herein the effect of electrical stimulation on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs) cultured on solid and nanoporous micropyramid patterned Si surfaces was evaluated. It was found that both stimulation and scaffold patterning significantly enhanced osteo-differentiation. The stimulated nanoporous micropyramid scaffolds were more promising compared to the stimulated solid micropyramid surfaces, as they significantly promoted the osteogenic differentiation of rBMSCs via BMP/Smad signaling pathway. Particularly, as compared to the unstimulated patterned biomaterials, the stimulated patterned scaffolds allowed for a significant increase in core binding factor alpha l, alkaline phosphatase, the alpha l chain of type I Col, osteocalcin, and osteonectin, all of which are characteristic for osteo-differentiation. The proposed combination of electrical stimulation with scaffold patterning may provide novel promising strategies for bone tissue engineering and regenerative medicine.

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

Electromagnetic fields (EMFs) have long been known to interact with living organisms and their cells and to bear the potential for therapeutic use. Among the most extensively investigated applications, the use of Pulsed EMFs (PEMFs) has proven effective to ameliorate bone healing in several studies, although the evidence is still inconclusive. This is due in part to our still-poor understanding of the mechanisms by which PEMFs act on cells and affect their functions and to an ongoing lack of consensus on the most effective parameters for specific clinical applications. The present review has compared in vitro studies on PEMFs on different osteoblast models, which elucidate potential mechanisms of action for PEMFs, up to the most recent insights into the role of primary cilia, and highlight the critical issues underlying at least some of the inconsistent results in the available literature. Bioelectromagnetics. 2019;9999:XX-XX. © 2019 Bioelectromagnetics Society.

A comprehensive overview on utilizing electromagnetic fields in bone regenerative medicine

Stem cells are one of the most important sources to develope  a new strategy for repairing bone lesions through tissue engineering. Osteogenic differentiation of stem cells can be affected by various factors such as biological, chemical, physiological, and physical ones. The application of ELF-EMFs has been the subject of many research in bone tissue engineering and evidence suggests that this exogenous physical stimulus can promote osteogenic differentiation in several types of  cells. The purpose of this paper is to review the current knowledge on the effects of EMFs on stem cells in bone tissue engineering studies. We recapitulated and analyzed 39 articles that were focused on the application of EMFs for bone tissue engineering purposes. We tabulated scattered information from these articles for easy use and tried to provide an overview of conducted research and identify the knowledge gaps in the field.

Electromagnetic Field Analysis of Low-Magnitude High-Frequency Vibrator with Multiple Plungers

Low-magnitude high-frequency (LMHF) of vibrational stimulation has been accepted as an effective method to enhance bone remolding. However, the electromagnetic field (EMF) generated by the vibrator could also be an influence factor in the vibrational experiments. This phenomenon underlies the bone remodeling effect caused by vibrational stimulation is disrupted to be investigated. This paper presents a design of LMHF vibrator with multiple plungers to generate vibrational stimulation with ultra low magnetic flux density to minimize the biological effect caused by the EMF. The EMF is analyzed in finite element method (FEM) using COMSOL.

Bioprocessing of Mesenchymal Stem Cells and Their Derivatives: Toward Cell-Free Therapeutics

Mesenchymal stem cells (MSCs) have attracted tremendous research interest due to their ability to repair tissues and reduce inflammation when implanted into a damaged or diseased site. These therapeutic effects have been largely attributed to the collection of biomolecules they secrete (i.e., their secretome). Recent studies have provided evidence that similar effects may be produced by utilizing only the secretome fraction containing extracellular vesicles (EVs). EVs are cell-derived, membrane-bound vesicles that contain various biomolecules. Due to their small size and relative mobility, they provide a stable mechanism to deliver biomolecules (i.e., biological signals) throughout an organism. The use of the MSC secretome, or its components, has advantages over the implantation of the MSCs themselves: (i) signals can be bioengineered and scaled to specific dosages, and (ii) the nonliving nature of the secretome enables it to be efficiently stored and transported. However, since the composition and therapeutic benefit of the secretome can be influenced by cell source, culture conditions, isolation methods, and storage conditions, there is a need for standardization of bioprocessing parameters. This review focuses on key parameters within the MSC culture environment that affect the nature and functionality of the secretome. This information is pertinent to the development of bioprocesses aimed at scaling up the production of secretome-derived products for their use as therapeutics.

The Use of Pulsed Electromagnetic Fields to Promote Bone Responses to Biomaterials In Vitro and In Vivo

Implantable biomaterials are extensively used to promote bone regeneration or support endosseous prosthesis in orthopedics and dentistry. Their use, however, would benefit from additional strategies to improve bone responses. Pulsed Electromagnetic Fields (PEMFs) have long been known to act on osteoblasts and bone, affecting their metabolism, in spite of our poor understanding of the underlying mechanisms. Hence, we have the hypothesis that PEMFs may also ameliorate cell responses to biomaterials, improving their growth, differentiation, and the expression of a mature phenotype and therefore increasing the tissue integration of the implanted devices and their clinical success. A broad range of settings used for PEMFs stimulation still represents a hurdle to better define treatment protocols and extensive research is needed to overcome this issue. The present review includes studies that investigated the effects of PEMFs on the response of bone cells to different classes of biomaterials and the reports that focused on in vivo investigations of biomaterials implanted in bone.

The legacy effects of electromagnetic fields on bone marrow mesenchymal stem cell self-renewal and multiple differentiation potential

Background

The effects of electromagnetic fields (EMF) on bone nonunion have been reported for many years. Many studies and randomized controlled trials have demonstrated that EMF exhibited benefits in curing delayed union and nonunion of long bone fractures. Most of them focused on the immediate effects, while the legacy effects of EMF remain poorly investigated.

Methods

In this study, rat bone marrow mesenchymal stem cells (BMSCs) were treated with EMF, and after a period of time the BMSC proliferation and differentiation were detected. Additionally, BMSC sheets with or without EMF treatment were transplanted into the rat tibia fracture nonunion models. The bone formation was evaluated after 2, 4, and 6 weeks.

Results

Our results showed that the proliferation capacity of BMSCs was heightened after EMF pretreatment. Over a period of time of EMF pretreatment, the capacities of osteogenic and chondrogenic differentiation were enhanced, while adipogenic differentiation was weakened. BMSC sheets pretreated with EMF could better promote the healing of tibia fracture in rats, compared to BMSC sheets alone. Furthermore, significantly higher values of radiographic grading scores were observed in the EMF group.

Conclusions

EMF has lasting effects on the proliferation and differentiation of BMSCs, and together with cell sheet technology can provide a new method for the treatment of fracture nonunion.

Electromagnetic transduction therapy in non-specific low back pain: A prospective randomised controlled trial

OBJECTIVES

A prospective randomised controlled trial to investigate the efficacy of electromagnetic transduction therapy (EMTT) for treatment of patients with non-specific low back pain.

DESIGN

Two groups with non-specific low back pain were either treated with conventional therapy alone over 6 weeks or in combination with 8 sessions of EMTT.

RESULTS

In both intervention groups the low back pain related pain and the degree of disability decreased significantly at follow-up visits. Combination of EMTT and conventional therapy proved significant superior to conventional therapy alone.

CONCLUSION

EMTT is a promising treatment in patients with non-specific low back pain.

Enhancement of osteogenic differentiation of rat adipose tissue-derived mesenchymal stem cells by zinc sulphate under electromagnetic field via the PKA, ERK1/2 and Wnt/β-catenin signaling pathways

Zinc ion as an essential trace element and electromagnetic fields (EMFs) has been reported to be involved in the regulation of bone metabolism. The aim of this study was to elucidate the effects of zinc sulphate (ZnSO₄) on the osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) in the presence of EMF as a strategy in osteoporosis therapy. Alkaline phophatase (ALP) activity measurement, calcium assay and expression of several osteoblastic marker genes were examined to assess the effect of ZnSO₄ on the osteogenic differentiation of ADSCs under EMF. The expression of cAMP and PKA was evaluated by ELISA. The expression of β-catenin, Wnt1, Wnt3a, low-density lipoprotein receptor-related protein 5 (LRP5) and reduced dickkopf1 (DKK1) genes were used to detect the Wnt/β-catenin pathway. It was found that ZnSO₄, in the presence of EMF, resulted in an increase in the expression of osteogenic genes, ALP activity and calcium levels. EMF, in the presence of ZnSO₄, increased the cAMP level and protein kinase A (PKA) activity. Treatment of ADSCs with (MAPK)/ERK kinase 1/2 inhibitor, or PKA inhibitor, significantly inhibited the promotion of osteogenic markers, indicating that the induction of osteogenesis was dependent on the ERK and PKA signaling pathways. Real-time PCR analysis showed that ZnSO₄, in the presence of EMF, increased the mRNA expressions of β-catenin, Wnt1, Wnt3a, LRP5 and DKK1. In this study, it was shown that 0.432 μg/ml ZnSO₄, in the presence of 50 Hz, 20 mT EMF, induced the osteogenic differentiation of ADSCs via PKA, ERK1/2 and Wnt/β-catenin signaling pathways.

Mesenchymal stem cells as therapeutic target of biophysical stimulation for the treatment of musculoskeletal disorders

BACKGROUND

Musculoskeletal disorders are regarded as a major cause of worldwide morbidity and disability, and they result in huge costs for national health care systems. Traditional therapies frequently turned out to be poorly effective in treating bone, cartilage, and tendon disorders or joint degeneration. As a consequence, the development of novel biological therapies that can treat more effectively these conditions should be the highest priority in regenerative medicine. Mesenchymal stem cells (MSCs) represent one of the most promising tools in musculoskeletal tissue regenerative medicine, thanks to their proliferation and differentiation potential and their immunomodulatory and trophic ability. Indeed, MSC-based approaches have been proposed for the treatment of almost all orthopedic conditions, starting from different cell sources, alone or in combination with scaffolds and growth factors, and in one-step or two-step procedures. While all these approaches would require cell harvesting and transplantation, the possibility to stimulate the endogenous MSCs to enhance their tissue homeostasis activity represents a less-invasive and cost-effective therapeutic strategy. Nowadays, the role of tissue-specific resident stem cells as possible therapeutic target in degenerative pathologies is underinvestigated. Biophysical stimulations, and in particular extracorporeal shock waves treatment and pulsed electromagnetic fields, are able to induce proliferation and support differentiation of MSCs from different origins and affect their paracrine production of growth factors and cytokines.

SHORT CONCLUSIONS

The present review reports the attempts to exploit the resident stem cell potential in musculoskeletal pathologies, highlighting the role of MSCs as therapeutic target of currently applied biophysical treatments.

Choice of osteoblast model critical for studying the effects of electromagnetic stimulation on osteogenesis in vitro

The clinical benefits of electromagnetic field (EMF) therapy in enhancing osteogenesis have been acknowledged for decades, but agreement regarding the underlying mechanisms continues to be sought. Studies have shown EMFs to promote osteoblast-like cell proliferation, or contrarily, to induce differentiation and enhance mineralization. Typically these disparities have been attributed to methodological differences. The present paper argues the possibility that the chosen osteoblast model impacts stimulation outcome. Phenotypically immature cells, particularly at low seeding densities, appear to be prone to EMF-amplified proliferation. Conversely, mature cells at higher densities seem to be predisposed to earlier onset differentiation and mineralization. This suggests that EMFs augment ongoing processes in cell populations. To test this hypothesis, mature SaOS-2 cells and immature MC3T3-E1 cells at various densities, with or without osteo-induction, were exposed to sinusoidal 50 Hz EMF. The exposure stimulated the proliferation of MC3T3-E1 and inhibited the proliferation of SaOS-2 cells. Baseline alkaline phosphatase (ALP) expression of SaOS-2 cells was high and rapidly further increased with EMF exposure, whereas ALP effects in MC3T3-E1 cells were not seen until the second week. Thus both cell types responded differently to EMF stimulation, corroborating the hypothesis that the phenotypic maturity and culture stage of cells influence stimulation outcome.

Biomineralization Guided by Paper Templates

This work demonstrates the fabrication of partially mineralized scaffolds fabricated in 3D shapes using paper by folding, and by supporting deposition of calcium phosphate by osteoblasts cultured in these scaffolds. This process generates centimeter-scale free-standing structures composed of paper supporting regions of calcium phosphate deposited by osteoblasts. This work is the first demonstration that paper can be used as a scaffold to induce template-guided mineralization by osteoblasts. Because paper has a porous structure, it allows transport of O₂ and nutrients across its entire thickness. Paper supports a uniform distribution of cells upon seeding in hydrogel matrices, and allows growth, remodelling, and proliferation of cells. Scaffolds made of paper make it possible to construct 3D tissue models easily by tuning material properties such as thickness, porosity, and density of chemical functional groups. Paper offers a new approach to study mechanisms of biomineralization, and perhaps ultimately new techniques to guide or accelerate the repair of bone.

How electromagnetic fields can influence adult stem cells: positive and negative impacts

The electromagnetic field (EMF) has a great impact on our body. It has been successfully used in physiotherapy for the treatment of bone disorders and osteoarthritis, as well as for cartilage regeneration or pain reduction. Recently, EMFs have also been applied in in vitro experiments on cell/stem cell cultures. Stem cells reside in almost all tissues within the human body, where they exhibit various potential. These cells are of great importance because they control homeostasis, regeneration, and healing. Nevertheless, stem cells when become cancer stem cells, may influence the pathological condition. In this article we review the current knowledge on the effects of EMFs on human adult stem cell biology, such as proliferation, the cell cycle, or differentiation. We present the characteristics of the EMFs used in miscellaneous assays. Most research has so far been performed during osteogenic and chondrogenic differentiation of mesenchymal stem cells. It has been demonstrated that the effects of EMF stimulation depend on the intensity and frequency of the EMF and the time of exposure to it. However, other factors may affect these processes, such as growth factors, reactive oxygen species, and so forth. Exploration of this research area may enhance the development of EMF-based technologies used in medical applications and thereby improve stem cell-based therapy and tissue engineering.

The effect of low-frequency electromagnetic field on human bone marrow stem/progenitor cell differentiation

Human bone marrow stromal cells (hBMSCs, also known as bone marrow-derived mesenchymal stem cells) are a population of progenitor cells that contain a subset of skeletal stem cells (hSSCs), able to recreate cartilage, bone, stroma that supports hematopoiesis and marrow adipocytes. As such, they have become an important resource in developing strategies for regenerative medicine and tissue engineering due to their self-renewal and differentiation capabilities. The differentiation of SSCs/BMSCs is dependent on exposure to biophysical and biochemical stimuli that favor early and rapid activation of the in vivo tissue repair process. Exposure to exogenous stimuli such as an electromagnetic field (EMF) can promote differentiation of SSCs/BMSCs via ion dynamics and small signaling molecules. The plasma membrane is often considered to be the main target for EMF signals and most results point to an effect on the rate of ion or ligand binding due to a receptor site acting as a modulator of signaling cascades. Ion fluxes are closely involved in differentiation control as stem cells move and grow in specific directions to form tissues and organs. EMF affects numerous biological functions such as gene expression, cell fate, and cell differentiation, but will only induce these effects within a certain range of low frequencies as well as low amplitudes. EMF has been reported to be effective in the enhancement of osteogenesis and chondrogenesis of hSSCs/BMSCs with no documented negative effects. Studies show specific EMF frequencies enhance hSSC/BMSC adherence, proliferation, differentiation, and viability, all of which play a key role in the use of hSSCs/BMSCs for tissue engineering. While many EMF studies report significant enhancement of the differentiation process, results differ depending on the experimental and environmental conditions. Here we review how specific EMF parameters (frequency, intensity, and time of exposure) significantly regulate hSSC/BMSC differentiation in vitro. We discuss optimal conditions and parameters for effective hSSC/BMSC differentiation using EMF treatment in an in vivo setting, and how these can be translated to clinical trials.