Pulsed Electromagnetic Field Regulates MicroRNA 21 Expression to Activate TGF-β Signaling in Human Bone Marrow Stromal Cells to Enhance Osteoblast Differentiation

Mangiferin- and GNPs/ECPP-loaded platform of UH with dual bi-directional dynamic modulation of stem cells/macrophages and osteoblasts/osteoclasts for the prevention of aseptic loosening

Aseptic inflammation and osteolysis triggered by the phagocytosis of implant wear particles by macrophages are important reasons for aseptic loosening (AL) in total joint replacement, which ultimately leads to implant failure. Therefore, the development of implants with long-term effectiveness in preventing AL is a pressing issue. In contrast to the conventional idea of reducing the occurrence of AL through anti-inflammatory treatment, we prepared implants based on a novel concept: to prevent AL by returning the dynamic balance of osteogenesis/osteolysis through dynamic modulation, which is expected to completely resolve the problem of AL. In this study, a natural polyphenol, mangiferin (MAN), and a composite filler (GNPs/ECPP) were loaded into ultrahigh-molecular-weight polyethylene (UH) to construct a hip implant component with the ability to prevent AL. This modified implant was able to improve the oxidation resistance and wear resistance of implants, which could reduce the production of wear particles, recruit BMSCs as well as promote their proliferation/osteogenic differentiation and inhibit macrophage activity and RANKL-induced macrophage osteoclast differentiation in vitro. These effects suggest that this modified implant has achieved the dual bi-directional dynamic modulation of stem cells/macrophages and osteoblasts/osteoclasts for the prevention of aseptic loosening. Notably, in vivo experiments for implantation of wear-particle-coated titanium rods demonstrated that wear particles from the prepared implant significantly promoted the osseointegration capacity of implanted prosthesis (titanium rod) and effectively inhibited peri-prosthesis osteolysis. This work provides a new concept and presents a promising way for the development of durable implant components with long-term protection against AL.

Impact of dcEF on microRNA profiles in glioblastoma and exosomes using a novel microfluidic bioreactor

Glioblastoma multiforme, the most common type of highly aggressive primary brain tumor, is influenced by complex molecular signaling pathways, where microRNAs (miRNAs) play a critical regulatory role. Originating from glial cells, glioblastoma cells are affected by the physiological direct current electric field (dcEF) in the central nervous system. While dcEF has been shown to affect glioblastoma migration (electrotaxis), the specific impact on glioblastoma intercellular communication and miRNA expression in glioblastoma cells and their exosomes remains unclear. This study aims to fill this gap by investigating the differential expression of microRNAs in glioblastoma cells and exosomes under dcEF stimulation. We have developed a novel, reversibly sealed dcEF stimulation bioreactor that ensures uniform dcEF stimulation across a large cell culture area, specifically targeting glioblastoma cells and primary human astrocytes. Using microarray analysis, we examined differential miRNA profiles in both cellular and exosomal RNAs. Our study identified shared molecular targets and pathways affected by dcEF stimulation. Our findings reveal significant changes in miRNA expression due to dcEF stimulation, with specific miRNAs, such as hsa-miR-4440 being up-regulated and hsa-miR-3201 and hsa-mir-548g being down-regulated. Future research will focus on elucidating the molecular mechanisms of these miRNAs and their potential as diagnostic biomarkers. The developed platform offers high-quality dcEF stimulation and rapid sample recovery, with potential applications in tissue engineering and multi-omics molecular analysis.

Photobiomodulation Modulates Proliferation and Gene Expression Related to Calcium Signaling in Human Osteoblast Cells

Introduction: Photobiomodulation with low-level laser treatment can enhance bone formation by stimulating the cell division of osteoblasts and increasing the amount of protein deposition, thus encouraging the formation of new bone. The aim of this study was to evaluate the effects of photobiomodulation with a low-level laser on proliferation and gene expression related to calcium signaling in human osteoblasts. Methods: Osteoblastic cell lines of the hFOB1.19 lineage, human osteoblasts, were grown and assigned into two groups, control (C; n=78 cultured wells) and photobiomodulation (L; n=78 cultured wells) with n=6 per day of the experimental period. Cells were cultured (immature at 34 ºC), and after maturation at 37 ºC, group L cells were exposed to laser irradiation with a low-level laser device (gallium and aluminum arsenide), at a wavelength of 808 nm, a power output of 200 mW, and a power density of 200 mW/cm2. The energy delivered to the cells was 37 J/cm2, with a beam area of 0.02 mm2 and an exposure time of 5 seconds. This treatment was applied daily for a period of 13 days. Following this, the number of cells was counted, and RNA was isolated, measured, and then converted into cDNA for further quantification using a comparative Ct method with real-time polymerase chain reaction. The results were then subjected to statistical analysis through a Mann-Whitney test, with a significance level of P<0.05. Results: The cell count in the L group (37.25x10±4±22.02) was statistically higher compared to the control group (22.75x10±4±7.660) with a P value of 0.0259. The values of 2-ΔΔCt for S100A6, plasma membrane calcium ATPase (PMCA), and calmodulin genes indicated hyper-expression on the thirteenth day, while the osteocalcin gene showed hypo-expression. Conclusion: The study suggests that the photobiomodulation mechanism with a low-level laser may regulate gene expression in human osteoblasts in a dose-dependent and cumulative manner.

Adjunctive Use of Bone Growth Stimulation Increases Cervical Spine Fusion Rates in Patients at Risk for Pseudarthrosis

STUDY DESIGN

A prospective multicenter clinical trial (NCT03177473) was conducted with a retrospective cohort used as a control arm.

OBJECTIVE

The purpose of this study was to evaluate cervical spine fusion rates in subjects with risk factors for pseudarthrosis who received pulsed electromagnetic field (PEMF) treatment.

SUMMARY OF BACKGROUND DATA

Certain risk factors predispose patients to pseudarthrosis, which is associated with prolonged pain, reduced function, and decreased quality of life.

METHODS

Subjects in the PEMF group were treated with PEMF for 6 months postoperatively. The primary outcome measure was fusion status at the 12-month follow-up period. Fusion status was determined using anterior/posterior, lateral, and flexion/extension radiographs and computed tomography (without contrast).

RESULTS

A total of 213 patients were evaluated (PEMF, n=160; Control, n=53). At baseline, the PEMF group had a higher percentage of subjects who used nicotine ( P =0.01), had osteoporosis ( P <0.05), multi-level disease ( P <0.0001), and were >65 years of age ( P =0.01). The PEMF group showed over two-fold higher percentage of subjects that had ≥3 risk factors (n=92/160, 57.5%) compared with the control group (n=14/53, 26.4%). At the 12-month follow-up, the PEMF group demonstrated significantly higher fusion rates compared with the control (90.0% vs. 60.4%, P <0.05). A statistically significant improvement in fusion rate was observed in PEMF subjects with multi-level surgery ( P <0.0001) and high BMI (>30 kg/m 2 ; P =0.0021) when compared with the control group. No significant safety concerns were observed.

CONCLUSIONS

Adjunctive use of PEMF stimulation provides significant improvements in cervical spine fusion rates in subjects having risk factors for pseudarthrosis. When compared with control subjects that did not use PEMF stimulation, treated subjects showed improved fusion outcomes despite being older, having more risk factors for pseudarthrosis, and undergoing more complex surgeries.

Clavicle fracture and triathlon performance: a case report

BACKGROUND

Collarbone fracture is a common injury, particularly among athletes involved in contact sports and participating in endurance activities. Conventional treatment requires surgery and postoperative immobilization, resulting in an average return-to-sport timeframe of approximately 13 weeks. This case challenges the established treatment protocols, aiming to expedite recovery and enable a quicker resumption of high-intensity athletic activities.

CASE PRESENTATION

A 24-year-old Caucasian athlete completed a Half-Ironman Triathlon (70.3) merely three weeks post-collarbone fracture. Utilizing Extracorporeal Magneto-Transduction Therapy (EMTT) alongside surgical intervention, the patient achieved accelerated healing and remarkable performance outcomes without encountering any adverse effects.

CONCLUSIONS

The integration of EMTT into the treatment paradigm for bone fractures alters the traditional understanding of recovery timelines and rehabilitation strategies. This case highlights the potential benefits of electromagnetic wave therapy in expediting the healing process and enabling athletes to resume high-level sports activities at an earlier stage.

Signalling pathways underlying pulsed electromagnetic fields in bone repair

Pulsed electromagnetic field (PEMF) stimulation is a prospective non-invasive and safe physical therapy strategy for accelerating bone repair. PEMFs can activate signalling pathways, modulate ion channels, and regulate the expression of bone-related genes to enhance osteoblast activity and promote the regeneration of neural and vascular tissues, thereby accelerating bone formation during bone repair. Although their mechanisms of action remain unclear, recent studies provide ample evidence of the effects of PEMF on bone repair. In this review, we present the progress of research exploring the effects of PEMF on bone repair and systematically elucidate the mechanisms involved in PEMF-induced bone repair. Additionally, the potential clinical significance of PEMF therapy in fracture healing is underscored. Thus, this review seeks to provide a sufficient theoretical basis for the application of PEMFs in bone repair.

Epigenetic regulation of bone remodeling and its role in the pathogenesis of primary osteoporosis

Discovery of molecular mechanisms of primary osteoporosis development is fundamental to understand the pathogenesis of musculoskeletal diseases in general and for identifying key links in the genetic and epigenetic regulation of bone remodelling genes. The number of identified molecular genetic markers for osteoporosis is increasing but there is a need to describe their functional interactions. These interactions have been determined to be associated with the control of expression of a number of transcription factors and the differentiation of mesenchymal stem cells through the pathway of osteoblastogenesis or adipogenesis, and monocytic precursors through the pathway of osteoclastogenesis. The results of epigenetic studies have significantly increased the understanding of the role of post-translational modifications of histones, DNA methylation and RNA interference in the osteoporosis pathogenesis and in bone remodelling. However, the knowledge should be systematised and generalised according to the results of research on the role of epigenetic modifiers in the development of osteoporosis, and the influence of each epigenetic mechanism on the individual links of bone remodelling during ontogenesis of humans in general, including the elderly, should be described. Understanding which mechanisms and systems are involved in the development of this nosology is of interest for the development of targeted therapies, as the possibility of using microRNAs to regulate genes is now being considered. Systematisation of these data is important to investigate the differences in epigenetic marker arrays by race and ethnicity. The review article analyses references to relevant reviews and original articles, classifies information on current advances in the study of epigenetic mechanisms in osteoporosis and reviews the results of studies of epigenetic mechanisms on individual links of bone remodelling.

Post-Transcriptional Regulatory Crosstalk between MicroRNAs and Canonical TGF-β/BMP Signalling Cascades on Osteoblast Lineage: A Comprehensive Review

MicroRNAs (miRNAs) are a family of small, single-stranded, and non-protein coding RNAs about 19 to 22 nucleotides in length, that have been reported to have important roles in the control of bone development. MiRNAs have a strong influence on osteoblast differentiation through stages of lineage commitment and maturation, as well as via controlling the activities of osteogenic signal transduction pathways. Generally, miRNAs may modulate cell stemness, proliferation, differentiation, and apoptosis by binding the 3'-untranslated regions (3'-UTRs) of the target genes, which then can subsequently undergo messenger RNA (mRNA) degradation or protein translational repression. MiRNAs manage the gene expression in osteogenic differentiation by regulating multiple signalling cascades and essential transcription factors, including the transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP), Wingless/Int-1(Wnt)/β-catenin, Notch, and Hedgehog signalling pathways; the Runt-related transcription factor 2 (RUNX2); and osterix (Osx). This shows that miRNAs are essential in regulating diverse osteoblast cell functions. TGF-βs and BMPs transduce signals and exert diverse functions in osteoblastogenesis, skeletal development and bone formation, bone homeostasis, and diseases. Herein, we highlighted the current state of in vitro and in vivo research describing miRNA regulation on the canonical TGF-β/BMP signalling, their effects on osteoblast linage, and understand their mechanism of action for the development of possible therapeutics. In this review, particular attention and comprehensive database searches are focused on related works published between the years 2000 to 2022, using the resources from PubMed, Google Scholar, Scopus, and Web of Science.

Pulse Electromagnetic Field for Treating Postmenopausal Osteoporosis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Postmenopausal osteoporosis is a type of chronic disease with high morbidity and high economic burden. Due to the adverse effects of long-term drug therapy, physical therapy, such as pulsed electromagnetic fields (PEMF), is widely implemented in clinical practice. Therefore, we first conducted the meta-analysis on the efficacy and safety of PEMF in the treatment of postmenopausal osteoporosis. We searched eight databases to acquire potentially eligible studies. Outcome indicators include bone mineral density (BMD), visual analogue scale (VAS), biochemical markers of alkaline phosphatase (ALP), osteocalcin, bone-specific alkaline phosphatase (BSAP), type I collagen carboxy-terminal peptide (CTX), and adverse events. The results showed that a total of 19 studies (1303 patients) were retrieved from eight databases. Compared with conventional medications, PEMF combined with conventional medications significantly increased BMD of lumbar vertebra, femoral, Ward's triangle, bone-specific biochemical indicators of ALP, BSAP, and osteocalcin, and relieved pain. However, The incidence of adverse events was not statistically significant between PEMF combined with conventional medications and conventional medications alone. Compared with conventional medications, PEMF significantly increased the BMD of the femur and reduced the degree of pain, but there was no statistical difference in the BMD of the lumbar spine between PEMF and placebo. Except osteocalcin, BSAP, CTX, and ALP showed no significant difference. In view of its efficacy and safety, PEMF intervention can be considered as a potentially effective complementary therapy for postmenopausal women with osteoporosis. © 2022 Bioelectromagnetics Society.

Coupling induction of osteogenesis and type H vessels by pulsed electromagnetic fields in ovariectomy-induced osteoporosis in mice

The growth of blood vessels and osteogenesis are coupled in bone tissue. A specialized subset of CD31^hiEndomucin^hi (CD31^hiEmcn^hi) vascular endothelium in bone has been identified to positively regulate bone formation. Pulsed electromagnetic field (PEMF) can promote the facture healing and reverse the loss of bone mass. However, the underlying mechanisms mediating in the positive effects of PEMF on bone mass accrual remain unclear. In the ovariectomized (OVX) osteoporotic mouse model, PEMF with specific parameters was administrated after 12 weeks of surgery and continued for 8 weeks. μCT analysis, quantitative PCR and Elisa assays were used to assess the PEMF-induced the osteogenesis, while immunostaining and flow cytometry were used to evaluate the abundance of CD31^hiEmcn^hi endothelium in the metaphysis near the growth plate. Administration of PEMF substantially countered OVX-induced bone loss as shown by greater trabecular bone, higher expression of Osterix, PDGFB and Col-1a1 transcripts, and modulation of bone anabolic and catabolic activity. The PEMF-induced osteogenesis was coupled by the expansion of CD31^hiEmcn^hi endothelium as demonstrated by CD31 and Endomucin double-positive immunostaining and flow cytometry. Concurrently, the higher level of HIF-α was found in PEMF-treated mice than in vehicle controls. Notably, inhibition of HIF-1α considerably reduced PEMF-induced osteogenesis, and led to a remarkable decrease of CD31^hiEmcn^hi vessels in the PEMF-treated OVX mice. The present study demonstrated the PEMF-induced coupling promotion of osteogenesis and CD31^hiEmcn^hi endothelial cells in a mouse model of postmenopausal osteoporosis. This coupling effect might be mediated in HIF-1α signaling in CD31^hiEmcn^hi endothelium. These findings open up new directions of al that might enable therapeutic improvement of osteogenesis in patients with osteoporosis.

miR-21-5p and canonical Wnt signaling pathway promote osteoblast function through a feed-forward loop induced by fluoride

Long-term excessive exposure to fluoride from environmental sources can cause serious public health problems such as dental fluorosis and skeletal fluorosis. The aberrant activation of osteoblasts in the early stage is one of the critical steps during the pathogenesis of skeletal fluorosis and canonical Wnt signaling pathway participate in the progress. However, the specific mechanism that how canonical Wnt signaling pathway was mediated is not yet clear. In this study, we found that miR-21-5p induced the activation of canonical Wnt signaling pathway via targeting PTEN and DKK2 during fluoride induced osteoblasts activation and firstly demonstrated the forward loop between canonical Wnt signaling and miR-21-5p in the process. These findings suggested an important regulatory role of miR-21-5p on canonical Wnt signaling pathway during skeletal fluorosis and miR-21-5p might be a potential therapeutic target for skeletal fluorosis.

Cellular stress response to extremely low-frequency electromagnetic fields (ELF-EMF): An explanation for controversial effects of ELF-EMF on apoptosis

Impaired apoptosis is one of the hallmarks of cancer, and almost all of the non‐surgical approaches of eradicating tumour cells somehow promote induction of apoptosis. Indeed, numerous studies have stated that non‐ionizing non‐thermal extremely low‐frequency magnetic fields (ELF‐MF) can modulate the induction of apoptosis in exposed cells; however, much controversy exists in observations. When cells are exposed to ELF‐EMF alone, very low or no statistically significant changes in apoptosis are observed. Contrarily, exposure to ELF‐EMF in the presence of a co‐stressor, including a chemotherapeutic agent or ionizing radiation, can either potentiate or inhibit apoptotic effects of the co‐stressor. In our idea, the main point neglected in interpreting these discrepancies is “the cellular stress responses” of cells following ELF‐EMF exposure and its interplay with apoptosis. The main purpose of the current review was to outline the triangle of ELF‐EMF, the cellular stress response of cells and apoptosis and to interpret and unify discrepancies in results based on it. Therefore, initially, we will describe studies performed on identifying the effect of ELF‐EMF on induction/inhibition of apoptosis and enumerate proposed pathways through which ELF‐EMF exposure may affect apoptosis; then, we will explain cellular stress response and cues for its induction in response to ELF‐EMF exposure; and finally, we will explain why such controversies have been observed by different investigators.

Evaluation of the Sensing Potential of Stem Cell-Secreted Proteins via a Microchip Device under Electromagnetic Field Stimulation

Most bone tissue engineering models fail to demonstrate the complex cellular functions of living bone; therefore, most translational studies on bone tissue are performed in live models. To reduce the need for live models, we developed a stimulated microchip model for monitoring protein secretion during osteogenesis using human mesenchymal stem cells (hMSCs). We established a bone microchip system for monitoring the in vitro differentiation and sensing the secreted proteins of hMSCs under a sinusoidal electromagnetic field (SEMF), which ameliorates bone healing in a biomimetic natural bone matrix. A 3 V-1 Hz SEMF biophysically stimulated osteogenesis by activating ERK-1/2 and promoting phosphorylation of p38 MAPK kinases. Exposure to a 3 V-1 Hz SEMF upregulated the expression of osteogenesis-related genes and enhanced the expression of key osteoregulatory proteins. We identified 23 proteins that were differentially expressed in stimulated human bone marrow mesenchymal stem cell secretomes or were absent in the control groups. Our on-chip stimulation technology is easy to use, versatile, and nondisruptive and should have diverse applications in regenerative medicine and cell-based therapies.

Combined Effects of Low-Frequency Pulsed Electromagnetic Field and Melatonin on Ovariectomy-Induced Bone Loss in Mice

Pulsed electromagnetic field (PEMF) therapy and melatonin (MEL) supplementation are expected to be important strategies for the treatment of osteoporosis. The aim of the current study was to investigate the efficacy of PEMF therapy, MEL supplementation, a combination of PEMF therapy, and MEL supplementation (PEMF + MEL) in mice with bilateral ovariectomy (OVX)-induced osteoporosis. Forty 12-week-old female C57/BL mice were randomly assigned to five groups (n = 8/group): OVX, PEMF, MEL, PEMF + MEL, and sham-operation (sham) groups. All mice in the first four groups were subjected to OVX. The mice in the PEMF and PEMF + MEL groups were exposed to PEMF (75 Hz, 1.6 mT, 1 h/day for 12 weeks), while those in the MEL and PEMF + MEL groups were administered MEL (50 mg/kg, i.p.). Body mass, micro-computed tomography, histology, immunohistochemistry, and real-time polymerase chain reaction were performed. PEMF + MEL treatment enhanced bone volume fraction (BV/TV) 2.2-fold over OVX control (P < 0.001) and increased expression levels of collagen type I (COL1) 1.9-fold and bone morphogenetic protein 2 (BMP2) 2.5-fold. PEMF + MEL also reduced the ratio of bone surface/bone volume (BS/BV) by 40% (P < 0.05) and appeared to reduce the number of osteoclasts in the metaphysis area. Preservation of bone value and bone microarchitecture in the combined therapy group were found to be superior to those in the single treatment groups. However, there were no apparent differences between the PEMF and MEL groups. The use of a combination of PEMF therapy and MEL supplementation may be an effective method to treat osteoporosis. © 2021 Bioelectromagnetics Society.

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.

Pulsed Electromagnetic Fields in Bone Healing: Molecular Pathways and Clinical Applications

In this article, we provide an extensive review of the recent literature of the signaling pathways modulated by Pulsed Electromagnetic Fields (PEMFs) and PEMFs clinical application. A review of the literature was performed on two medical electronic databases (PubMed and Embase) from 3 to 5 March 2021. Three authors performed the evaluation of the studies and the data extraction. All studies for this review were selected following these inclusion criteria: studies written in English, studies available in full text and studies published in peer-reviewed journal. Molecular biology, identifying cell membrane receptors and pathways involved in bone healing, and studying PEMFs target of action are giving a solid basis for clinical applications of PEMFs. However, further biology studies and clinical trials with clear and standardized parameters (intensity, frequency, dose, duration, type of coil) are required to clarify the precise dose-response relationship and to understand the real applications in clinical practice of PEMFs.

Exposure to 16 Hz Pulsed Electromagnetic Fields Protect the Structural Integrity of Primary Cilia and Associated TGF-β Signaling in Osteoprogenitor Cells Harmed by Cigarette Smoke

Cigarette smoking (CS) is one of the main factors related to avoidable diseases and death across the world. Cigarette smoke consists of numerous toxic compounds that contribute to the development of osteoporosis and fracture nonunion. Exposure to pulsed electromagnetic fields (PEMF) was proven to be a safe and effective therapy to support bone fracture healing. The aims of this study were to investigate if extremely low frequency (ELF-) PEMFs may be beneficial to treat CS-related bone disease, and which effect the duration of the exposure has. In this study, immortalized human mesenchymal stem cells (SCP-1 cells) impaired by 5% cigarette smoke extract (CSE) were exposed to ELF-PEMFs (16 Hz) with daily exposure ranging from 7 min to 90 min. Cell viability, adhesion, and spreading were evaluated by Sulforhodamine B, Calcein-AM staining, and Phalloidin-TRITC/Hoechst 33342 staining. A migration assay kit was used to determine cell migration. Changes in TGF-β signaling were evaluated with an adenoviral Smad2/3 reporter assay, RT-PCR, and Western blot. The structure and distribution of primary cilia were analyzed with immunofluorescent staining. Our data indicate that 30 min daily exposure to a specific ELF-PEMF most effectively promoted cell viability, enhanced cell adhesion and spreading, accelerated migration, and protected TGF-β signaling from CSE-induced harm. In summary, the current results provide evidence that ELF-PEMF can be used to support early bone healing in patients who smoke.

Pulsed Electromagnetic Fields Modulate miRNAs During Osteogenic Differentiation of Bone Mesenchymal Stem Cells: a Possible Role in the Osteogenic-angiogenic Coupling

Despite the high intrinsic ability of bone tissue to regenerate, bone healing fails in some pathological conditions and especially in the presence of large defects. Due to the strong relationship between bone development and vascularization during in vivo bone formation and repair, strategies promoting the osteogenic-angiogenic coupling are crucial for regenerative medicine. Increasing evidence shows that miRNAs play important roles in controlling osteogenesis and bone vascularization and are important tool in medical research although their clinical use still needs to optimize miRNA stability and delivery. Pulsed electromagnetic fields (PEMFs) have been successfully used to enhance bone repair and their clinical activity has been associated to their ability to promote the osteogenic differentiation of human mesenchymal stem cells (hMSCs). In this study we investigated the potential ability of PEMF exposure to modulate selected miRNAs involved in the osteogenic differentiation of human bone mesenchymal stem cells (hBMSCs). We show that, during in vitro hBMSC differentiation, PEMFs up-modulate the expression of miR-26a and miR-29b, which favor osteogenic differentiation, and decrease miR-125b which acts as an inhibitor miRNA. As PEMFs promote the expression and release of miRNAs also involved in angiogenesis, we conclude that PEMFs may represent a noninvasive and safe strategy to modulate miRNAs with relevant roles in bone repair and with the potential to regulate the osteogenic-angiogenic coupling.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

3D‑printed Ti6Al4V scaffolds combined with pulse electromagnetic fields enhance osseointegration in osteoporosis

The loosening and displacement of prostheses after dental implantation and arthroplasty is a substantial medical burden due to the complex correction surgery. Three-dimensional (3D)-printed porous titanium (pTi) alloy scaffolds are characterized by low stiffness, are beneficial to bone ingrowth, and may be used in orthopedic applications. However, for the bio-inert nature between host bone and implants, titanium alloy remains poorly compatible with osseointegration, especially in disease conditions, such as osteoporosis. In the present study, 3D-printed pTi scaffolds with ideal pore size and porosity matching the bone tissue, were combined with pulse electromagnetic fields (PEMF), an exogenous osteogenic induction stimulation, to evaluate osseointegration in osteoporosis. In vitro, external PEMF significantly improved osteoporosis-derived bone marrow mesenchymal stem cell proliferation and osteogenic differentiation on the surface of pTi scaffolds by enhancing the expression of alkaline phosphatase, runt-related transcription factor-2, osteocalcin, and bone morphogenetic protein-2. In vivo, Microcomputed tomography analysis and histological evaluation indicated the external PEMF markedly enhanced bone regeneration and osseointegration. This novel therapeutic strategy has potential to promote osseointegration of dental implants or artificial prostheses for patients with osteoporosis.

Electromagnetic field and TGF-β enhance the compensatory plasticity after sensory nerve injury in cockroach Periplaneta americana

Recovery of function after sensory nerves injury involves compensatory plasticity, which can be observed in invertebrates. The aim of the study was the evaluation of compensatory plasticity in the cockroach (Periplaneta americana) nervous system after the sensory nerve injury and assessment of the effect of electromagnetic field exposure (EMF, 50 Hz, 7 mT) and TGF-β on this process. The bioelectrical activities of nerves (pre-and post-synaptic parts of the sensory path) were recorded under wind stimulation of the cerci before and after right cercus ablation and in insects exposed to EMF and treated with TGF-β. Ablation of the right cercus caused an increase of activity of the left presynaptic part of the sensory path. Exposure to EMF and TGF-β induced an increase of activity in both parts of the sensory path. This suggests strengthening effects of EMF and TGF-β on the insect ability to recognize stimuli after one cercus ablation. Data from locomotor tests proved electrophysiological results. The takeover of the function of one cercus by the second one proves the existence of compensatory plasticity in the cockroach escape system, which makes it a good model for studying compensatory plasticity. We recommend further research on EMF as a useful factor in neurorehabilitation.

MicroRNAs Modulate Signaling Pathways in Osteogenic Differentiation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have been identified in many adult tissues and they have been closely studied in recent years, especially in view of their potential use for treating diseases and damaged tissues and organs. MSCs are capable of self-replication and differentiation into osteoblasts and are considered an important source of cells in tissue engineering for bone regeneration. Several epigenetic factors are believed to play a role in the osteogenic differentiation of MSCs, including microRNAs (miRNAs). MiRNAs are small, single-stranded, non-coding RNAs of approximately 22 nucleotides that are able to regulate cell proliferation, differentiation and apoptosis by binding the 3' untranslated region (3'-UTR) of target mRNAs, which can be subsequently degraded or translationally silenced. MiRNAs control gene expression in osteogenic differentiation by regulating two crucial signaling cascades in osteogenesis: the transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP) and the Wingless/Int-1(Wnt)/β-catenin signaling pathways. This review provides an overview of the miRNAs involved in osteogenic differentiation and how these miRNAs could regulate the expression of target genes.

Pulsed-electromagnetic-field induced osteoblast differentiation requires activation of genes downstream of adenosine receptors A2A and A3

Pulsed-electromagnetic-field (PEMF) treatment was found to enhance cellular differentiation of the mouse preosteoblast, MC3T3-E1, to a more osteoblastic phenotype. Differentiation genes such as Alp, BSPI, cFos, Ibsp, Osteocalcin, Pthr1 and Runx2 showed increased expression in response to PEMF stimulation. Detailed molecular mechanisms linking PEMF to the activation of these genes are limited. Two adenosine receptors known to be modulated in response to PEMF, Adora2A and Adora3, were functionally impaired by CRISPR-Cas9-mediated gene disruption, and the consequences of which were studied in the context of PEMF-mediated osteoblastic differentiation. Disruption of Adora2A resulted in a delay of Alp mRNA expression, but not alkaline phosphatase protein expression, which was similar to that found in wild type cells. However, Adora3 disruption resulted in significantly reduced responses at both the alkaline phosphatase mRNA and protein levels throughout the PEMF stimulation period. Defects observed in response to PEMF were mirrored using a chemically defined growth and differentiation-inducing media (DM). Moreover, in cells with Adora2A disruption, gene expression profiles showed a blunted response in cFos and Pthr1 to PEMF treatment; whereas cells with Adora3 disruption had mostly blunted responses in AlpI, BSPI, Ibsp, Osteocalcin and Sp7 gene activation. To demonstrate specificity for Adora3 function, the Adora3 open reading frame was inserted into the ROSA26 locus in Adora3 disrupted cells culminating in rescued PEMF responsiveness and thereby eliminating the possibility of off-target effects. These results lead us to propose that there are complementary and parallel positive roles for adenosine receptor A_2A and A₃ in PEMF-mediated osteoblast differentiation.

Pulsed electromagnetic field (PEMF) transiently stimulates the rate of mineralization in a 3-dimensional ring culture model of osteogenesis

Pulsed Electromagnetic Field (PEMF) has shown efficacy in bone repair and yet the optimum characteristics of this modality and its molecular mechanism remain unclear. To determine the effects of timing of PEMF treatment, we present a novel three-dimensional culture model of osteogenesis that demonstrates strong de novo generation of collagen and mineral matrix and exhibits stimulation by PEMF in multiple stages over 62 days of culture. Mouse postnatal day 2 calvarial pre-osteoblasts were cast within and around Teflon rings by polymerization of fibrinogen and cultured suspended without contact with tissue culture plastic. Ring constructs were exposed to PEMF for 4h/day for the entire culture (Daily), or just during Day1-Day10, Day11-Day 27, or Day28-Day63 and cultured without PEMF for the preceding or remaining days, and compared to no-PEMF controls. PEMF was conducted as HF Physio, 40.85 kHz frequency with a 67 ms burst period and an amplitude of 1.19 mT. Osteogenesis was kinetically monitored by repeated fluorescence measurements of continuously present Alizarin Red S (ARS) and periodically confirmed by micro-CT. PEMF treatment induced early-onset and statistically significant transient stimulation (~4-fold) of the mineralization rate when PEMF was applied Daily, or during D1-D10 and D11-D27. Stimulation was apparent but not significant between D28-D63 by ARS but was significant at D63 by micro-CT. PEMF also shifted the micro-CT density profiles to higher densities in each PEMF treatment group. Ring culture generated tissue with a mineral:matrix ratio of 2.0 by thermogravimetric analysis (80% of the calvaria control), and the deposited crystal structure was 50% hydroxyapatite by X-ray diffraction (63% of the calvaria and femur controls), independent of PEMF. These results were consistent with backscatter, secondary electron, and elemental analysis by scanning electron microscopy. Thus, in a defined, strong osteogenic environment, PEMF applied at different times was capable of further stimulation of osteogenesis with the potential to enhance bone repair.

Therapeutic effect of pulsed electromagnetic field on bone wound healing in rats

This study aimed to investigate the therapeutic effect of pulsed electromagnetic field (PEMF) on bone wound in rats as a potential therapy for bone fracture-related conditions. Male rats, aged 3 months, were used to construct model of bone wounding. Wound models were randomly selected to receive PEMF therapy at 1 to 10 mT intensity. Models that did not receive PEMF therapy were used as control. The serum concentrations of calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) were determined. Bone density and biomechanical properties of callus were measured using a tensile tester. Compared with control, rats subjected to PEMF therapy had similar weight gain, but significantly higher levels of serum Ca and ALP (P < .05) at 5 and 10 mT, while the serum level of P remained unchanged after PEMF therapy. The bone mineral density of callus increased after the therapy, particularly, after 5 and 10 mT therapy (P < .05). Biomechanical measurements showed that 21 days after the therapy, the maximum load, fracture load, elastic load and bending energy were significantly greater in rats receiving 5 and 10 mT PEMF therapy as compared with control (P < .05). Our experiments demonstrate that PEMF at 5 and 10 mT can significantly accelerate wound healing and enhance the repairing ability of bone tissue.

[Pathophysiological mechanisms of the therapeutic action of alternating electromagnetic fields in the treatment of osteoarticular pathology]

Treatment of osteoarticular pathology with an alternating electromagnetic field (AEMF) is used today as a promising, non-invasive and safe strategy of physiotherapy. It has been shown that the action of alternating electromagnetic fields on the musculoskeletal system triggers signaling cascades that effectively contribute to the restoration of bone and articular tissue. The pathophysiological mechanisms underlying the cellular and subcellular effects of stimulation by an alternating electromagnetic field during the restoration of bone and articular tissue are considered. It was pointed out the several key signaling pathways involved in the restoration of bone and articular tissue under the influence of electromagnetic fields with an analysis of the potential for therapeutic application of electromagnetic fields alone or in combination with other available therapies.

The effect of extremely low frequency electromagnetic fields following on upregulation of miR-21 and miR-29 in gastric cancer cell line

AIM

Extremely low frequency electromagnetic fields affect miRNAs expression in cancer cell. In this study, electromagnetic fields exposed to low frequency were used to compare miR-21 and miR-29 expressions in a gastric cancer cell line.

BACKGROUND

It has been recently suggested that the low frequency electromagnetic fields probably function as a treatment for cancers.

METHODS

A cultured cell line of gastric cancer was exposed to an electromagnetic radiation system. The cell line was assigned to 4 groups under continuous and discontinuous radiations of 0.25 and 2.5 ml Tesla field strength. Then, the groups were compared with a non-radiation control group. Later, RNA extraction and cDNA synthesis were prepared for miR-21 and miR-29. Real Time PCR method was used to determine how expressions of these two microRNAs differ. Finally, the results were statistically analyzed.

RESULTS

The percentage of cell viability in the electromagnetic field radiation experienced a significant decrease compared to that of the control group. In addition, expression of miRNA-21 and miRNA-29 had a significant increase as the strength of the electromagnetic field radiations was on an upward trend. Similarly, the percentage of cell viability saw a significant decline in the upregulation of miRNA-21 and miRNA-29 regardless of radiation types.

CONCLUSION

Findings of this study showed the therapeutic effect of low frequency electromagnetic fields on the gastric cancer cell line. They also indicated that novel biomarkers (miRNA-21 and miRNA-29) could be proposed as potential treatments of gastric cancer, but the results are required to be well established by future studies.

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.

MicroRNA-21-Enriched Exosomes as Epigenetic Regulators in Melanomagenesis and Melanoma Progression: The Impact of Western Lifestyle Factors

DNA mutation-induced activation of RAS-BRAF-MEK-ERK signaling associated with intermittent or chronic ultraviolet (UV) irradiation cannot exclusively explain the excessive increase of malignant melanoma (MM) incidence since the 1950s. Malignant conversion of a melanocyte to an MM cell and metastatic MM is associated with a steady increase in microRNA-21 (miR-21). At the epigenetic level, miR-21 inhibits key tumor suppressors of the RAS-BRAF signaling pathway enhancing proliferation and MM progression. Increased MM cell levels of miR-21 either result from endogenous upregulation of melanocytic miR-21 expression or by uptake of miR-21-enriched exogenous exosomes. Based on epidemiological data and translational evidence, this review provides deeper insights into environmentally and metabolically induced exosomal miR-21 trafficking beyond UV-irradiation in melanomagenesis and MM progression. Sources of miR-21-enriched exosomes include UV-irradiated keratinocytes, adipocyte-derived exosomes in obesity, airway epithelium-derived exosomes generated by smoking and pollution, diet-related exosomes and inflammation-induced exosomes, which may synergistically increase the exosomal miR-21 burden of the melanocyte, the transformed MM cell and its tumor environment. Several therapeutic agents that suppress MM cell growth and proliferation attenuate miR-21 expression. These include miR-21 antagonists, metformin, kinase inhibitors, beta-blockers, vitamin D, and plant-derived bioactive compounds, which may represent new options for the prevention and treatment of MM.

MicroRNA-1-3p enhances osteoblast differentiation of MC3T3-E1 cells by interacting with hypoxia-inducible factor 1 α inhibitor (HIF1AN)

Studies have proved that miRNAs participate in the regulation of osteoblast differentiation (OD), and abnormal expression of miRNAs is related with various states of OD. In this study, we investigated the role of miRNA-1-3p in OD using MC3T3-E1 cells. BMP2 is used to induce OD of MC3T3-E1 cells. MiRNA-1-3p mimics or miRNA-1-3p inhibitor was transfected to MC3T3-E1 cells with BMP2. The expression levels of miRNA-1-3p were determined by qRT-PCR. The expression of Runx2, OSX, OPN, and OCN was detected by Western blotting. ALP assay was performed to measure alkaline phosphatase activity. Calcium nodules were evaluated by alizarin red staining. Over-expression of hypoxia-inducible factor 1-alpha inhibitor (HIF1AN) was performed and miRNA-1-3p rescue experiments were carried out. Over-expression of miRNA-1-3p promoted osteogenic differentiations and calcifications, as demonstrated by increased ALP, calcification and osteogenic markers. Knock-down of miRNA-1-3p generated the opposite results. HIF1AN was identified to be directly targeted by miRNA-1-3p. Over-expression of HIF1AN suppressed OD and calcifications, and miRNA-1-3p reversed the effect. Our results demonstrated that miRNA-1-3p could enhance OD of MC3T3-E1 cells through interacting with HIF1AN, which might be employed as therapeutic applications for bone formation and regeneration.

Role and mechanism of micro-energy treatment in regenerative medicine

With the continuous integration and intersection of life sciences, engineering and physics, the application for micro-energy in the basic and clinical research of regenerative medicine (RM) has made great progress. As a key target in the field of RM, stem cells have been widely used in the studies of regeneration. Recent studies have shown that micro-energy can regulate the biological behavior of stem cells to repair and regenerate injured organs and tissues by mechanical stimulation with appropriate intensity. Integrins-mediated related signaling pathways may play important roles in transducing mechanical force about micro-energy. However, the complete mechanism of mechanical force transduction needs further research. The purpose of this article is to review the biological effect and mechanism of micro-energy treatment on stem cells, to provide reference for further research.

An osteoinductive effect of phytol on mouse mesenchymal stem cells (C3H10T1/2) towards osteoblasts

In recent years, phytochemicals have been widely researched and utilized for the treatment of various medical conditions such as cancer, cardiovascular diseases, age-related problems and are also said to have bone regenerative effects. In this study, phytol (3,7,11,15-tetramethylhexadec-2-en-1-ol), an acyclic unsaturated diterpene alcohol and a secondary metabolite derived from aromatic plants was investigated for its effect on osteogenesis. Phytol was found to be nontoxic in mouse mesenchymal stem cells (C3H10T1/2). At the cellular level, phytol-treatment promoted osteoblast differentiation, as seen by the increased calcium deposits. At the molecular level, phytol-treatment stimulated the expression of Runx2 (a bone-related transcription factor) and other osteogenic marker genes. MicroRNAs (miRNAs) play an essential role in controlling bone metabolism by targeting genes at the post-transcriptional level. Upon phytol-treatment in C3H10T1/2 cells, mir-21a and Smad7 levels were increased and decreased, respectively. It was previously reported that mir-21a targets Smad7 (an antagonist of TGF-beta1 signaling) and thus, protects Runx2 from its degradation. Thus, based on our results, we suggest that phytol-treatment promoted osteoblast differentiation in C3H10T1/2 cells via Runx2 due to downregulation of Smad7 by mir-21a. Henceforth, phytol was identified to bolster osteoblast differentiation, which in turn may be used for bone regeneration.

Identification of key microRNAs and target genes for the diagnosis of bone nonunion

A number of recent studies have highlighted the causes of bone nonunion (BN), however, the rate of BN incidence continues to rise and available therapeutic options to treat this condition remain limited. Thus, to prevent disease progression and improve patient prognosis, it is vital that BN, or the risk thereof, be accurately identified in a timely manner. In the present study, bioinformatics analyses were used to screen for the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) between patients with BN and those with bone union, using data from the Gene Expression Omnibus database. Furthermore, clinical samples were collected and analyzed by reverse transcription‑quantitative PCR and western blotting. In vitro and in vivo experiments were carried out to confirm the relationship between BN and the DEGs of interest, in addition to being used to explore the underlying molecular mechanism of BN. Functional enrichment analysis of the downregulated DEGs revealed them to be enriched for genes associated with 'ECM‑receptor interactions', 'focal adhesion', 'and the calcium signaling pathway'. When comparing DEM target genes with these DEGs, nine DEGs were identified as putative DEM targets, where hsa‑microRNA (miR)‑1225‑5p‑CCNL2, hsa‑miR‑339‑5p‑PRCP, and hsa‑miR‑193a‑3p‑mitogen‑activated protein kinase 10 (MAPK10) were the only three pairs which were associated with decreased gene expression levels. Furthermore, hsa‑miR‑193a‑3p was demonstrated to induce BN by targeting MAPK10. Collectively, the results of the present study suggest that hsa‑miR‑193a‑3p may be a viable biomarker of BN.

Regulation of Runx2 by post-translational modifications in osteoblast differentiation

Osteogenesis is the process of new bone formation where transcription factors play an important role in controlling cell proliferation and differentiation. Runt-related transcription factor 2 (Runx2), a key transcription factor, regulates the differentiation of mesenchymal stem cells into osteoblasts, which further mature into osteocytes. Runx2 acts as a modulator such that it can either stimulate or inhibit the osteoblast differentiation. A defect/alteration in the expression/activity of this gene may lead to skeletal dysplasia. Runx2 thus serves as the best therapeutic model gene for studying bone and bone-related diseases. In this review, we briefly outline the regulation of Runx2 and its activity at the post-translational levels by the virtue of phosphorylation, acetylation, and ubiquitination in controlling the bone homeostasis.

3D-Printed β-Tricalcium Phosphate Scaffold Combined with a Pulse Electromagnetic Field Promotes the Repair of Skull Defects in Rats

Trauma, infection, cancer, and congenital diseases can lead to bone defects. The combination of 3D printing with biomaterials is of great significance in the treatment of bone defects. In addition, pulse electromagnetic fields (PEMFs) can promote bone regeneration. The main purpose of this study was to evaluate the effects of 3D-printed scaffolds using β-tricalcium phosphate (β-TCP) as the raw material combined with a PEMF on the proliferation and differentiation of rat adipose stem cells (rADSCs) and on the repair of critical defects of the rat skull. The Cell Counting Kit-8 assay was performed to assess the proliferation of rADSCs. Alkaline phosphatase (ALP) activity, ALP staining, and the detection of osteogenic-related gene expression were performed to assess the differentiation of rADSCs. Micro-computed tomography and hematoxylin-eosin staining were used to assess the repair of rat skull defects. The results showed that the combination of the scaffold and PEMF could significantly promote the proliferation and differentiation of rADSCs and the repair of a critical defect in the rat skull. Therefore, the combination of β-TCP and PEMF with 3D printing technology can provide better treatment of clinical bone defect patients.

Hypoxia-responsive miRNA-21-5p inhibits Runx2 suppression by targeting SMAD7 in MC3T3-E1 cells

Sustained hypoxia inhibits osteogenesis and osteoblast differentiation by downregulating the expression of runt‐related transcription factor 2 (Runx2). MicroRNAs (miRNAs) have been shown to regulate osteogenesis and osteoblast differentiation. In the present study, we profiled miRNAs, with microRNA array and quantitative real‐time polymerase chain reaction (RT‐PCR) methods, in mouse osteoblast (MC3T3‐E1) cells under hypoxia. Then, we investigated regulation by miRNA‐21‐5p on the expression of Runx2 and other osteoblast differentiation‐associated markers via gain‐of‐function and loss‐of‐function strategies. We found that expression of miRNA‐21‐5p, miRNA‐210‐5p, and other eight miRNAs was upregulated significantly in hypoxia‐treated MC3T3‐E1 cells. miRNA‐21‐5p overexpression downregulated the expression of the mRNA and protein of suppressor of mothers against decapentaplegic (SMAD7) markedly, the 3′‐untranslated region (3′‐UTR) of which was highly homologous with the miRNA‐21‐5p sequence. miRNA‐21‐5p overexpression upregulated the protein expression of Runx2 in hypoxia‐treated MC3T3‐E1 cells, although mRNA expression of Runx2 and other osteoblast differentiation‐associated molecules (eg, osteocalcin, procollagen type 1 amino‐terminal propeptide, P1NP) were not regulated by it; such upregulation was SMAD7‐dependent. In conclusion, hypoxia‐responsive miRNA‐21‐5p promoted Runx2 expression (at least in part) by targeting the 3′‐UTR and downregulating SMAD7 expression. Our study suggests a protective role of miRNA‐21‐5p in promoting osteoblast differentiation under hypoxia.

Role of microRNAs in osteogenesis of stem cells

Osteogenic differentiation is a controlled developmental process in which external and internal factors including cytokines, growth factors, transcription factors (TFs), signaling pathways and microRNAs (miRNAs) play important roles. Various stimulatory and inhibitory TFs contribute to osteogenic differentiation and are responsible for bone development. In addition, cross-talk between several complex signaling pathways regulates the osteogenic differentiation of some stem cells. Although much is known about regulatory genes and signaling pathways in osteogenesis, the role of miRNAs in osteogenic differentiation still needs to be explored. miRNAs are small, approximately 22 nucleotides, single-stranded nonprotein coding RNAs which are abundant in many mammalian cell types. They paly significant regulated roles in various biological processes and serve as promising biomarkers for disease states. Recently, emerging evidence have shown that miRNAs are the key regulators of osteogenesis of stem cells. They may endogenously regulate osteogenic differentiation of stem cells through direct targeting of positive or negative directors of osteogenesis and depending on the target result in the promotion or inhibition of osteogenic differentiation. This review aims to provide a general overview of miRNAs participating in osteogenic differentiation of stem cells and explain their regulatory effect based on the genes targeted with these miRNAs.

Retracted: Downregulation of microRNA-367 promotes osteoblasts growth and proliferation of mice during fracture by activating the PANX3-mediated Wnt/β-catenin pathway

A majority of people suffering from bone fractures fail to heal and develop a nonunion, which is a challenging orthopedic complication requiring complex and expensive treatment. Previous data showed the inhibition of some microRNAs (miRNAs or miRs) can enhance fracture healing. The objective of the present study is to explore effects of miR-367 on the osteoblasts growth and proliferation of mouse during fracture via the Wnt/β-catenin pathway by targeting PANX3. Primarily, the femur fracture model was successfully established in 66 (C57BL/6) 6-week-old male mice. To verify whether miR-367 target PANX3, we used the target prediction program and performed luciferase activity determination. Subsequently, to figure out the underlying regulatory roles of miR-367 in fracture, osteoblasts were elucidated by treatment with miR-367 mimic, miR-367 inhibitor, or siRNA against PANX3 to determine the expression of miR-367, siPANX3, β-catenin, and Wnt5b as well as cell proliferation and apoptosis. The results demonstrated that PANX3 was verified as a target gene of miR-367. MiR-367 was found to highly expressed but PANX3, β-catenin, and Wnt5b were observed poorly expressed in fracture mice. downregulated miR-367 increased the mRNA and protein expression of PANX3, β-catenin, and Wnt5b, increased cell growth, proliferation, and migration, while decreased cell apoptosis in osteoblasts. Altogether, our study demonstrates that the downregulation of miR-367 may promote osteoblasts growth and proliferation in fracture through the activation of the PANX3-dependent Wnt/β-catenin pathway.

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.

Pulsed electromagnetic fields modulate bone metabolism via RANKL/OPG and Wnt/β-catenin pathways in women with postmenopausal osteoporosis: A pilot study

Pulsed electromagnetic fields (PEMFs) have been proven to enhance in vitro and in vivo osteogenesis with unknown mechanism. Aim of our study was to explore whether RANKL/OPG and Wnt/β-Catenin pathways could be involved in bone response to PEMFs in a setting of postmenopausal osteoporotic women. Forty-three women (mean age 62.8 ± 4.5 yr.) were randomized into two groups. The PEMFs group received PEMFs treatment (50 min treatment session/day, 6 treatment sessions/week, for a total of 25 times), by wearing a specific gilet applied to the trunk and connected to the electromagnetic device (Biosalus, by HSD Srl, Serravalle RSM), while women assigned to control group received sham PEMFs with the same device. BSAP as bone formation and CTX as bone resorption markers, RANKL, OPG, β-Catenin, DKK-1 and sclerostin were obtained at baseline, after 30 and 60 days. In PEMFs group, BSAP levels significantly increased after 30 and 60 days while CTX concentrations decreased at day 60. RANKL levels significantly decreased after 60 days. OPG was not significantly changed, but the RANKL/OPG ratio significantly decreased at day 30. DKK-1 levels decreased, while β-catenin concentrations increased after 30 and 60 days (P < 0.05). No significant changes of calcium, phosphorus, creatinine and sclerostin were detected. In the PEMFs group, at day 30, Δsclerostin was associated with ΔRANKL/OPG ratio (r = -0.5, P = 0.03) and ΔDKK-1 was associated with Δβ-Catenin (r = -0.47, P = 0.02). In women with postmenopausal osteoporosis, our data provide evidence of a PEMFs modulation of RANKL/OPG and Wnt/β-Catenin signaling pathways able to explain the metabolic effects of PEMFs on bone.

miR-335-5p induces insulin resistance and pancreatic islet β-cell secretion in gestational diabetes mellitus mice through VASH1-mediated TGF-β signaling pathway

Multiple studies have reported different methods in treating gestational diabetes mellitus (GDM); however, the relationship between miR-335-5p and GDM still remains unclear. Here, this study explores the effect of miR-335-5p on insulin resistance and pancreatic islet β-cell secretion via activation of the TGFβ signaling pathway by downregulating VASH1 expression in GDM mice. The GDM mouse model was established and mainly treated with miR-335-5p mimic, miR-335-5p inhibitor, si-VASH1, and miR-335-5p inhibitor + si-VASH1. Oral glucose tolerance test (OGTT) was conducted to detect fasting blood glucose (FBG) fasting insulin (FINS). The OGTT was also used to calculate a homeostasis model assessment of insulin resistance (HOMA-IR). A hyperglycemic clamp was performed to measure the glucose infusion rate (GIR), which estimated β-cell function. Expressions of miR-335-5p, VASH1, TGF-β1, and c-Myc in pancreatic islet β-cells were determined by RT-qPCR, western blot analysis, and insulin release by ELISA. The miR-335-5p mimic and si-VASH1 groups showed elevated blood glucose levels, glucose area under the curve (GAUC), and HOMA-IR, but a reduced GIR and positive expression of VASH1. Overexpression of miR-335-5p and inhibition of VASH1 contributed to activated TGFβ1 pathway, higher c-Myc, and lower VASH1 expressions, in addition to downregulated insulin and insulin release levels. These findings provided evidence that miR-335-5p enhanced insulin resistance and suppressed pancreatic islet β-cell secretion by inhibiting VASH1, eventually activating the TGF-β pathway in GDM mice, which provides more clinical insight on the GDM treatment.

Magnetic Resonance Spectroscopy for Evaluating the Effect of Pulsed Electromagnetic Fields on Marrow Adiposity in Postmenopausal Women With Osteopenia

OBJECTIVE

Pulsed electromagnetic fields (PEMFs) could promote osteogenic differentiation and suppress adipogenic differentiation in bone mesenchymal stem cells ex vivo. However, data on the effect of PEMF on marrow adiposity in humans remain elusive. We aimed to determine the in vivo effect of PEMF on marrow adiposity in postmenopausal women using magnetic resonance spectroscopy.

METHODS

Sixty-one postmenopausal women with osteopenia, aged 53 to 85 years, were randomly assigned to receive either PEMF treatment or placebo. The session was performed 3 times per week for 6 months. All women received adequate dietary calcium and vitamin D. Bone mineral density (BMD) by dual-energy x-ray absorptiometry, vertebral marrow fat content by magnetic resonance spectroscopy, and serum biomarkers were evaluated before and after 6 months of treatment.

RESULTS

A total of 27 (87.1%) and 25 (83.3%) women completed the treatment schedule in the PEMF and placebo groups, respectively. After the 6-month treatment, lumbar spine and hip BMD increased by 1.46% to 2.04%, serum bone-specific alkaline phosphatase increased by 3.23%, and C-terminal telopeptides of type 1 collagen decreased by 9.12% in the PEMF group (P < 0.05), whereas the mean percentage changes in BMD and serum biomarkers were not significant in the placebo group. Pulsed electromagnetic field treatment significantly reduced marrow fat fraction by 4.81%. The treatment difference between the 2 groups was -4.43% (95% confidence interval, -3.70% to -5.65%; P = 0.009).

CONCLUSIONS

Pulsed electromagnetic field is an effective physiotherapy in postmenopausal women, and this effect may, at least in part, regulate the amount of fat within the bone marrow. Magnetic resonance spectroscopy may serve as a complementary imaging biomarker for monitoring response to therapy in osteoporosis.

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.

Syringic acid, a phenolic acid, promotes osteoblast differentiation by stimulation of Runx2 expression and targeting of Smad7 by miR-21 in mouse mesenchymal stem cells

Syringic acid (SA), a phenolic acid, has been used in Chinese and Indian medicine for treating diabetes but its role in osteogenesis has not yet been investigated. In the present study, at the molecular and cellular levels, we evaluated the effects of SA on osteoblast differentiation. At the cellular level, there was increased alkaline phosphatase (ALP) activity and calcium deposition by SA treatment in mouse mesenchymal stem cells (mMSCs). At the molecular level, SA treatment of these cells stimulated expression of Runx2, a bone transcription factor, and of osteoblast differentiation marker genes such as ALP, type I collagen, and osteocalcin. It is known that Smad7 is an antagonist of TGF-β/Smad signaling and is a negative regulator of Runx2. microRNAs (miRNAs) play a key role in the regulation of osteogenesis genes at the post-transcriptional level and studies have reported that Smad7 is one of the target genes of miR-21. We found that there was down regulation of Smad7 and up regulation of miR-21 in SA-treated mMSCs. We further identified that the 3'-untranslated region (UTR) of Smad7 was directly targeted by miR-21 in these cells. Thus, our results suggested that SA promotes osteoblast differentiation via increased expression of Runx2 by miR-21-mediated down regulation of Smad7. Hence, SA may have potential in orthopedic applications.

The Effects of a Pulsed Electromagnetic Field on the Proliferation and Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Background

A low frequency pulsed electromagnetic field (PEMF) has been confirmed to play an important role in promoting the osteogenic differentiation of human bone marrow stem cells (BMSCs). Adipose-derived stem cells (ASCs) possess some attractive characteristics for clinical application compared to BMSCs, such as abundant stem cells from lipoaspirates, faster growth, less discomfort and morbidity during surgery. ASCs can become adipocytes, osteoblasts, chondrocytes, myocytes, neurocytes, and other cell types. Thus, ASCs might be a good alternative in clinical work involving treatment with PEMF.

Material/Methods

Human ASCs (hASCs)were divided into a control group (without PEMF exposure) and an experimental group (PEMF for two hours per day). We examined the effect of PEMF on promoting cell proliferation and osteogenic differentiation from several aspects: CCK-8 proliferation assay, RNA extraction, qRT-PCR detection, western blotting, and immunofluorescence staining experiments.

Results

PEMF could promote cell proliferation of human ASCs (hASCs) at an early stage as determined by CCK-8 assay. A specific intensity (1 mT) and frequency (50 Hz) of PEMF promoted osteogenic differentiation in hASCs in alkaline phosphatase (ALP) staining experiments. In addition, bone-related gene expression increased after two weeks of PEMF exposure, the protein expression of OPN, OCN, and RUNX-2 also increased after a longer period (three weeks) of PEMF treatment as determined by western blotting and immunofluorescence staining.

Conclusions

We found for the first time that PMEF has a role in stimulating cell proliferation of hASCs at an early period, subsequently promoting bone-related gene expression and inducing the expression of related proteins to stimulate osteogenic differentiation.

Parathyroid hormone-induced down-regulation of miR-532-5p for matrix metalloproteinase-13 expression in rat osteoblasts

Parathyroid hormone (PTH) acts on osteoblasts and functions as an essential regulator of calcium homeostasis and as a mediator of bone remodeling. We previously reported that PTH stimulates the expression of matrix metalloproteinase-13 (MMP-13) in rat osteoblasts and that MMP-13 plays a key role in bone remodeling, endochondral bone formation, and bone repair. Recent evidence indicated that microRNAs (miRNAs) have regulatory functions in bone metabolism. In this study, we hypothesized that the down-regulation of miRNAs that target MMP-13 by PTH leads to the stimulation of MMP-13 expression in osteoblasts. We used various bioinformatic tools to identify miRNAs that putatively target rat MMP-13. Among these miRNAs, the expression of miR-532-5p in rat osteoblasts decreased at 4 h of PTH-treatment, whereas MMP-13 mRNA expression was maximal at the same time point. When an miR-532-5p mimic was transiently transfected into UMR-106-01 cells, MMP-13 mRNA and protein expression decreased. Using a luciferase reporter assay system, we also identified that miR-532-5p directly targeted the 3' UTRs of MMP-13 gene. Based on these results, we suggest that PTH-induced down-regulation of miR-532-5p resulted in the stimulation of MMP-13 expression in rat osteoblasts. This study identified a significant role of miRNA in controlling bone remodeling via PTH-stimulated MMP-13 expression. This finding enhances our understanding of bone metabolism and bone-related diseases and it could provide information regarding the usage of miRNAs as therapeutic agents or biomarkers.

Pulsed electromagnetic fields inhibit human osteoclast formation and gene expression via osteoblasts

Pulsed electromagnetic fields (PEMFs) can be effective in promoting the healing of delayed union or nonunion fractures. We previously reported that PEMF (Spinal-Stim® by Orthofix, Inc., Lewisville, TX) stimulated proliferation, differentiation and mineralization of rat calvarial osteoblastic cells in culture. In the present work we investigated the effects of PEMF (Physio-Stim® by Orthofix, Inc., Lewisville, TX) on human bone marrow macrophages (hBMMs) differentiated to osteoclasts. PEMF had striking inhibitory effects on formation of osteoclasts from hBMMs from both younger and older women. There were significantly greater changes in gene expression as ascertained by RNAseq from cells from older women. Interestingly, all of the genes identified by RNAseq were upregulated, and all were genes of mesenchymal or osteoblastic cells and included members of the TGF-β signaling pathway and many extracellular matrix proteins, as well as RANKL and osteoprotegerin, indicating the mixed nature of these cultures. From these results, we suggest that PEMF can inhibit osteoclast formation via action on osteoblasts. Thus, PEMF may be very effective for bone mass maintenance in subjects with osteoporosis.

Physical stimulation and scaffold composition efficiently support osteogenic differentiation of mesenchymal stem cells

BACKGROUND

Despite significant achievements in the field of tissue engineering, simplification and improvement of the existing protocols are of great importance. The use of complex differentiation media, due to the presence of multiple factors, may have some undesired effects on cell health and functions. Thus, minimizing the number of involved factors, while maintaining the differentiation efficiency, provides less costly and controllable conditions. Adipose-derived Mesenchymal stem cells (ASCs), the adult stem cells present in adipose tissue, can be a suitable source of stem cells due to abundant and ease of access. The aim of this study is to optimize the osteogenic differentiation of ASCs by chemical composition of scaffold, in the first step, and then by electromagnetic treatments.

METHODS

ASCs were cultured on PVA/PES scaffold and tissue culture polystyrene surfaces (TCPS) and osteogenic differentiation was performed with either osteogenic medium, or electromagnetic field or both. The impact of each treatment on ASCs growth and proliferation was measured by MTT assay. Changes in gene expression levels of osteogenic-specific markers including ALP and RUNX2 were determined by Real Time PCR. Furthermore, alkaline phosphatase activity and calcium deposition were measured.

RESULTS

The MTT assay showed the significant effects on cell growth and respiration in scaffold-seeded ASCs treated with electromagnetic field, compared to control TCPS plate. Also, the electromagnetic treatment, increased alkaline phosphatase activity and calcium deposition. Finally, Real Time PCR showed higher expression of ALP and RUNX2 genes in electromagnetic field groups compared to control groups.

CONCLUSION

It can be concluded that PVA/PES scaffold used in this study improved the osteogenic capacity of ASCs. Moreover, the osteogenic potential of ASCs seeded on PVA/PES scaffold could be augmented by electromagnetic field without any chemical stimulation.

Effects of Electrostatic Field on Osteoblast Cells for Bone Regeneration Applications

Many external stimulations have been shown to promote bone regeneration. The effects of an alternating current (AC) electrostatic field, one of external stimulations, generated from a device with high voltage and low current output on human osteoblastic cell line have been investigated in this study. We investigated how human osteoblasts responded to an AC electrostatic field, and the output parameters were set as 1 kV and 160 μA. Our results showed that, under such condition, the AC electrostatic field had a downregulation effect on the production ability of alkaline phosphatase and type 1 collagen expression. However, the expression of osteocalcin gene was elevated on the end of EFID treatment suggesting that AC electrostatic field might be a potential stimulation for accelerating the differentiation of osteoblastic cells.

Pulsed electromagnetic field applications: A corporate perspective

Corporate establishment of US Food & Drug Administration approved pulsed electromagnetic fields (PEMFs) for clinical applications has been achieved. However, optimization of PEMFs for improvement in efficacy for current indications, in addition to the expansion into new indications, is not trivial. Moving directly into a clinical trial can be costly and carries little guarantee for success, necessitating the need for preclinical studies as supported by this review of the extensive corporate preclinical experience by Orthofix, Inc. The Translational Potential of this Article: This review illustrates the need to gain enough in vitro/in vivo knowledge of specific PEMF signals and its target tissue interaction to enable a high success rate in clinical trials.