The preventive effects of pulsed electromagnetic fields on diabetic bone loss in streptozotocin-treated rats

Effects of 3.5-GHz radiofrequency radiation on energy-regulatory hormone levels in the blood and adipose tissue

In recent years exposure of living beings to radiofrequency radiation (RFR) emitted from wireless equipment has increased. In this study, we investigated the effects of 3.5-GHz RFR on hormones that regulate energy metabolism in the body. Twenty-eight rats were divided into four groups: healthy sham (n = 7), healthy RFR (n = 7), diabetic sham (n = 7), and diabetic RFR (n = 7). Over a month, each group spent 2 h/day in a Plexiglas carousel. The rats in the experimental group were exposed to RFR, but the sham groups were not. At the end of the experiment, blood and adipose tissues were collected from euthanized rats. Total antioxidant, total oxidant, hydrogen peroxide, ghrelin, nesfatin-1, and irisin were determined. Insulin expression in pancreatic tissues was examined by immunohistochemical analysis. Whole body specific absorption rate was 37 mW/kg. For the parameters analyzed in blood and fat, the estimated effect size varied within the ranges of 0.215-0.929 and 0.503-0.839, respectively. The blood and adipose nesfatin-1 (p = 0.002), blood and pancreatic insulin are decreased, (p = 0.001), gherelin (p = 0.020), irisin (p = 0.020), and blood glucose (p = 0.040) are increased in healthy and diabetic rats exposed to RFR. While nesfatin-1 are negatively correlated with oxidative stress, hyperglycemia and insulin, ghrelin and irisin are positively correlated with oxidative stress and hyperglycemia. Thus, RFR may have deleterious effects on energy metabolism, particularly in the presence of diabetes.

Promising application of pulsed electromagnetic fields on tissue repair and regeneration

Tissue repair and regeneration is a vital biological process in organisms, which is influenced by various internal mechanisms and microenvironments. Pulsed electromagnetic fields (PEMFs) are becoming a potential medical technology due to its advantages of effectiveness and non-invasiveness. Numerous studies have demonstrated that PEMFs can stimulate stem cell proliferation and differentiation, regulate inflammatory reactions, accelerate wound healing, which is of great significance for tissue regeneration and repair, providing a solid basis for enlarging its clinical application. However, some important issues such as optimal parameter system and potential deep mechanisms remain to be resolved due to PEMFs window effect and biological complexity. Thus, it is of great importance to comprehensively summarizing and analyzing the literature related to the biological effects of PEMFs in tissue regeneration and repair. This review expounded the biological effects of PEMFs on stem cells, inflammation response, wound healing and musculoskeletal disorders in order to improve the application value of PEMFs in medicine. It is believed that with the continuous exploration of biological effects of PEMFs, it will be applied increasingly widely to tissue repair and other diseases.

Early protection against bone stress injuries by mobilization of endogenous targeted bone remodeling

Bone stress injuries are common overuse injuries, especially in soldiers, athletes, and performers. In contrast to various post-injury treatments, early protection against bone stress injuries can provide greater benefit. This study explored the early protection strategies against bone stress injuries by mobilization of endogenous targeted bone remodeling. The effects of various pharmaceutical/biophysical approaches, individual or combinational, were investigated by giving intervention before fatigue loading. We optimized the dosage and administration parameters and found that early intervention with pulsed electromagnetic field and parathyroid hormone (i.e., PEMF+PTH) resulted in the most pronounced protective effects among all the approaches against the bone stress injuries. In addition, the mechanisms by which the strategy mobilizes targeted bone remodeling and enhances the self-repair capacity of bone were systematically investigated. This study proposes strategies to reduce the incidence of bone stress injuries in high-risk populations (e.g., soldiers and athletes), particularly for those before sudden increased physical training.

Bone Deterioration in Response to Chronic High-Altitude Hypoxia Is Attenuated by a Pulsed Electromagnetic Field Via the Primary Cilium/HIF-1α Axis

Chronic high-altitude hypoxia induces irreversible abnormalities in various organisms. Emerging evidence indicates that hypobaric hypoxia markedly suppresses bone mass and bone strength. However, few effective means have been identified to prevent such bone deficits. Here, we assessed the potential of pulsed electromagnetic fields (PEMFs) to noninvasively resist bone deterioration induced by hypobaric hypoxia. We observed that exogenous PEMF treatment at 15 Hz and 20 Gauss (Gs) improved the cancellous and cortical bone mass, bone microstructure, and skeletal mechano-properties in rats subjected to chronic exposure of hypobaric hypoxia simulating an altitude of 4500 m for 6 weeks by primarily modulating osteoblasts and osteoblast-mediated bone-forming activity. Moreover, our results showed that whereas PEMF stimulated the functional activity of primary osteoblasts in hypoxic culture in vitro, it had negligible effects on osteoclasts and osteocytes exposed to hypoxia. Mechanistically, the primary cilium was found to function as the major electromagnetic sensor in osteoblasts exposed to hypoxia. The polycystins PC-1/PC-2 complex was identified as the primary calcium channel in the primary cilium of hypoxia-exposed osteoblastic cells responsible for the detection of external PEMF signals, and thereby translated these biophysical signals into intracellular biochemical events involving significant increase in the intracellular soluble adenylyl cyclase (sAC) expression and subsequent elevation of cyclic adenosine monophosphate (cAMP) concentration. The second messenger cAMP inhibited the transcription of oxygen homeostasis-related hypoxia-inducible factor 1-alpha (HIF-1α), and thus enhanced osteoblast differentiation and improved bone phenotype. Overall, the present study not only advances our understanding of bone physiology at high altitudes, but more importantly, proposes effective means to ameliorate high altitude-induced bone loss in a noninvasive and cost-effective manner. © 2023 American Society for Bone and Mineral Research (ASBMR).

Pulsed electromagnetic fields inhibit mandibular bone deterioration depending on the Wnt3a/β-catenin signaling activation in type 2 diabetic db/db mice

Type 2 diabetes mellitus (T2DM) patients have compromised mandibular bone architecture/quality, which markedly increase the risks of tooth loosening, tooth loss, and failure of dental implantation. However, it remains lacks effective and safe countermeasures against T2DM-related mandibular bone deterioration. Herein, we studied the effects of pulsed electromagnetic fields (PEMF) on mandibular bone microstructure/quality and relevant regulatory mechanisms in T2DM db/db mice. PEMF exposure (20 Gs, 15 Hz) for 12 weeks preserved trabecular bone architecture, increased cortical bone thickness, improved material properties and stimulated bone anabolism in mandibles of db/db mice. PEMF also upregulated the expression of canonical Wnt3a ligand (but not Wnt1 or Wnt5a) and its downstream β-catenin. PEMF improved the viability and differentiation of primary osteoblasts isolated from the db/db mouse mandible, and stimulated the specific activation of Wnt3a/β-catenin signaling. These positive effects of PEMF on mandibular osteoblasts of db/db mice were almost totally abolished after Wnt3a silencing in vitro, which were equivalent to the effects following blockade of canonical Wnt signaling using the broad-spectrum antagonist DKK1. Injection with Wnt3a siRNA abrogated the therapeutic effects of PEMF on mandibular bone quantity/quality and bone anabolism in db/db mice. Our study indicates that PEMF might become a non-invasive and safe treatment alternative resisting mandibular bone deterioration in T2DM patients, which is helpful for protecting teeth from loosening/loss and securing the dental implant stability.

Pulsed Electro-Magnetic Field (PEMF) Effect on Bone Healing in Animal Models: A Review of Its Efficacy Related to Different Type of Damage

Simple Summary

Pulsed electromagnetic fields (PEMFs) are a type of biophysical stimulation that has been shown to be effective in improving bone regeneration and preventing bone loss. Their use dates back to the 1970s, but a gold standard treatment protocol has not yet been defined. PEMF efficacy relies on the generation of biopotentials, which activate several molecular pathways. There is currently no clear understanding of the effects on bone healing and, in addition, there are several animal models relevant to this issue. Therefore, drawing guidelines and conclusions from the analysis of the studies is difficult. In vivo investigations on PEMF stimulation are reviewed in this paper, focusing on molecular and morphological improvements in bone. Currently, there is little knowledge about the biological mechanism of PEMF and its effect on bone healing. This is due to the variability of crucial characteristics of electro-magnetic fields, such as amplitude and exposure frequency, which may influence the type of biological response. Furthermore, a different responsiveness of cells involved in the bone healing process is documented. Heterogeneous setting parameters and different outcome measures are considered in various animal models. Therefore, achieving comparable results is difficult.

Abstract

Biophysical energies are a versatile tool to stimulate tissues by generating biopotentials. In particular, pulsed electromagnetic field (PEMF) stimulation has intrigued researchers since the 1970s. To date, many investigations have been carried out in vivo, but a gold standard treatment protocol has not yet been defined. The main obstacles are represented by the complex setting of PEMF characteristics, the variety of animal models (including direct and indirect bone damage) and the lack of a complete understanding of the molecular pathways involved. In the present review the main studies about PEMF stimulation in animal models with bone impairment were reviewed. PEMF signal characteristics were investigated, as well as their effect on molecular pathways and osseous morphological features. We believe that this review might be a useful starting point for a prospective study in a clinical setting. Consistent evidence from the literature suggests a potential beneficial role of PEMF in clinical practice. Nevertheless, the wide variability of selected parameters (frequency, duration, and amplitude) and the heterogeneity of applied protocols make it difficult to draw certain conclusions about PEMF effectiveness in clinical implementation to promote bone healing. Deepening the knowledge regarding the most consistent results reported in literature to date, we believe that this review may be a useful starting point to propose standardized experimental guidelines. This might provide a solid base for further controlled trials, to investigate PEMF efficacy in bone damage conditions during routine clinical practice.

Protective effects of low-magnitude high-frequency vibration on high glucose-induced osteoblast dysfunction and bone loss in diabetic rats

Objective

Low-magnitude high-frequency vibration (LMHFV) has been reported to be capable of promoting osteoblast proliferation and differentiation. Reduced osteoblast activity and impaired bone formation were related to diabetic bone loss. We investigated the potential protective effects of LMHFV on high-glucose (HG)-induced osteoblasts in this study. In addition, the assessment of LMHFV treatment for bone loss attributed to diabetes was also performed in vivo.

Method

MC3T3-E1 cells induced by HG only or treated with LMHFV were treated in vitro. The experiments performed in this study included the detection of cell proliferation, migration and differentiation, as well as protein expression. Diabetic bone loss induced by streptozotocin (STZ) in rats was established. Combined with bone morphometric, microstructure, biomechanical properties and matrix composition tests, the potential of LMHFV in treating diabetes bone loss was explored.

Results

After the application of LMHFV, the inhibiting effects of HG on the proliferation, migration and differentiation of osteoblasts were alleviated. The GSK3β/β-catenin pathway was involved in the protective effect of LMHFV. Impaired microstructure and biomechanical properties attributed to diabetes were ameliorated by LMHFV treatment. The improvement of femur biomechanical properties might be associated with the alteration of the matrix composition by the LMHFV.

Conclusion

LMHFV exhibited a protective effect on osteoblasts against HG by regulating the proliferation, migration and differentiation of osteoblasts. The function of promoting bone formation and reinforcing bone strength made it possible for LMHFV to alleviate diabetic bone loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02803-w.

The effect of magnetic therapy and moderate aerobic exercise on osteoporotic patients: A randomized clinical study

BACKGROUND

Osteoporosis is a frequent musculoskeletal condition with significant complications that would be a global health problem and one of the major causes of mortality and morbidity.

OBJECTIVES

The current study aimed to ascertain the impact of pulsed magnetic therapy, aerobic exercise, and a combination of both modalities on osteoporotic female patients postthyroidectomy.

METHODS

Between May 2018 and September 2019, 45 female patients with osteoporosis were included in the randomized clinical study, their age ranged from 40 to 50 years, had thyroidectomy for at least 6 months ago, and had an inactive lifestyle for at least the previous 6 months. Patients were assigned randomly into 3 equal groups. Group A (magnetic therapy group): received routine medical treatment (bisphosphonates, calcium, and vitamin D) in addition to pulsed magnetic therapy on the hip region for 12 weeks (3 sessions/week). Group B (exercise group): received routine medical treatment plus moderate-intensity aerobic exercise for 12 weeks (3 sessions/week). Group C (combined magnetic therapy and exercise therapy group): received routine medical treatment plus pulsed magnetic therapy and moderate-intensity aerobic exercise for 12 weeks (3 sessions/week). The 3 groups were assessed for bone mineral density (BMD) at baseline by dual-energy x-ray absorptiometry and after 12 weeks of treatment.

RESULTS

The results showed that within-group analysis a statistically significant increase was reveled (P < .05) for BMD in the 3 studied groups. Comparing the results among the 3 tested groups revealed a significant increase (P < .05) in posttesting mean values of BMD in group (C) compared to group (A) and group (B). No significant statistical difference in BMD means values between the 2 groups (A) and (B) after testing was detected.

CONCLUSION

Combination of both pulsed magnetic therapy and moderate-intensity aerobic exercise showed significant improvement in BMD at the hip region than using any of the 2 modalities alone.

Efficacy of Pulsed Electromagnetic Fields on Experimental Osteopenia in Rodents: A Systematic Review

Osteoporosis leads to increased bone fragility and risk of fractures. Different strategies have been employed to reduce bone loss, including the use of a pulsed electromagnetic field (PEMF). Although many experimental studies have demonstrated the effect of PEMF on reduction of bone loss, the outcomes studied are varied and insufficient, and the quality of evidence is unknown. Therefore, the aim of this review was to assess the preclinical evidence on the effect of PEMF on bone loss. The existing challenges were also evaluated, and suggestions were provided to strengthen the quality of evidence in future studies. All original articles concerning the effect of PEMF on osteoporosis in animal models were included. Twenty-four studies met the inclusion criteria, 23 of which suggested that PEMF was effective in reducing bone loss, while one study failed to demonstrate any benefit. Risk of bias analysis suggested that information on key measures to reduce bias was frequently not reported. Animal models for osteoporosis, PEMF intervention regimens, outcomes, and specific bone detection sites seemed to influence the efficacy of PEMF in osteoporosis. Our results indicate the potential benefits of PEMF selection in animal models of osteoporosis. However, due to the heterogeneity of the parameters and the quality of the included literature, comprehensive studies using standardized protocols are warranted to confirm the results. © 2021 Bioelectromagnetics Society.

A Low-Frequency Pulsed Magnetic Field Reduces Neuropathic Pain by Regulating NaV1.8 and NaV1.9 Sodium Channels at the Transcriptional Level in Diabetic Rats

Low-frequency pulsed magnetic field (LF-PMF) application is a non-invasive, easy, and inexpensive treatment method in pain management. However, the molecular mechanism underlying the effect of LF-PMF on pain is not fully understood. Considering the obvious dysregulations of gene expression observed in certain types of voltage-gated sodium channels (VGSCs) in pain conditions, the present study tested the hypothesis that LF-PMF shows its pain-relieving effect by regulating genes that code VGSCs proteins. Five experimental rat groups (Control, Streptozotocin-induced experimental painful diabetic neuropathy (PDN), PDN Sham, PDN 10 Hz PMF, and PDN 30 Hz PMF) were established. After the pain formation in PDN groups, the magnetic field groups were exposed to 10/30 Hz, 1.5 mT PMF for 4 weeks, an hour daily. Progression of pain was evaluated using behavioral pain tests during the entire experimental processes. After the end of PMF treatment, SCN9A (NaV_1.7 ), SCN10A (NaV_1.8 ), SCN11A (NaV_1.9 ), and SCN3A (NaV_1.3 ) gene expression level changes were determined by analyzing real-time polymerase chain reaction results. We found that 10 Hz PMF application was more effective than 30 Hz on pain management. In addition, NaV_1.7 and NaV_1.3 transcriptions were upregulated while NaV_1.8 and NaV_1.9 were downregulated in painful conditions. Notably, the downregulated expression of the genes encoding NaV_1.8 and NaV_1.9 were re-regulated and increased to control level by 10 Hz PMF application. Consequently, it may be deduced that 10 Hz PMF application reduces pain by modulating certain VGSCs at the transcriptional level. © 2021 Bioelectromagnetics Society.

Spatiotemporal characterization of microdamage accumulation and its targeted remodeling mechanisms in diabetic fatigued bone

The skeleton of type 1 diabetes mellitus (T1DM) has deteriorated mechanical integrity and increased fragility, whereas the mechanisms are not fully understood. Load-induced microdamage naturally occurs in bone matrix and can be removed by initiating endogenous targeted bone remodeling. However, the microdamage accumulation in diabetic skeleton and the corresponding bone remodeling mechanisms remain poorly understood. Herein, streptozotocin-induced T1DM rats and age-matched non-diabetic rats were subjected to daily uniaxial ulnar loading for 1, 4, 7, and 10 days, respectively. The SPECT/CT and basic fuchsin staining revealed significant higher-density spatial accumulation of linear and diffuse microdamage in diabetic ulnae than non-diabetic ulnae. Linear microcracks increased within 10-day loading in diabetic bone, whereas peaked at Day 7 in non-diabetic bone. Moreover, diabetic fatigued ulnae had more severe disruptions of osteocyte canaliculi around linear microcracks. Immunostaining results revealed that diabetes impaired targeted remodeling in fatigued bone at every key stage, including increased apoptosis of bystander osteocytes, decreased RANKL secretion, reduced osteoclast recruitment and bone resorption, and impaired osteoblast-mediated bone formation. This study characterizes microdamage accumulation and abnormal remodeling mechanisms in the diabetic skeleton, which advances our etiologic understanding of diabetic bone deterioration and increased fragility from the aspect of microdamage accumulation and bone remodeling.

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.

Pulsed electromagnetic field and relief of hypoxia-induced neuronal cell death: The signaling pathway

Low-energy low-frequency pulsed electromagnetic fields (PEMFs) exert several protective effects, such as the regulation of kinases, transcription factors as well as cell viability in both central and peripheral biological systems. However, it is not clear on which bases they affect neuroprotection and the mechanism responsible is yet unknown. In this study, we have characterized in nerve growth factor-differentiated pheochromocytoma PC12 cells injured with hypoxia: (i) the effects of PEMF exposure on cell vitality; (ii) the protective pathways activated by PEMFs to relief neuronal cell death, including adenylyl cyclase, phospholipase C, protein kinase C epsilon and delta, p38, ERK1/2, JNK1/2 mitogen-activated protein kinases, Akt and caspase-3; (iii) the regulation by PEMFs of prosurvival heat-shock proteins of 70 (HSP70), cAMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), and Bcl-2 family proteins. The results obtained in this study show a protective effect of PEMFs that are able to reduce neuronal cell death induced by hypoxia by modulating p38, HSP70, CREB, BDNF, and Bcl-2 family proteins. Specifically, we found a rapid activation (30 min) of p38 kinase cascade, which in turns enrolles HSP70 survival chaperone molecule, resulting in a significant CREB phosphorylation increase (24 hr). In this cascade, later (48 hr), BDNF and the antiapoptotic pathway regulated by the Bcl-2 family of proteins are recruited by PEMFs to enhance neuronal survival. This study paves the way to elucidate the mechanisms triggered by PEMFs to act as a new neuroprotective approach to treat cerebral ischemia by reducing neuronal cell death.

Pulsed electromagnetic fields: promising treatment for osteoporosis

Osteoporosis (OP) is considered to be a well-defined disease which results in high morbidity and mortality. In patients diagnosed with OP, low bone mass and fragile bone strength have been demonstrated to significantly increase risk of fragility fractures. To date, various anabolic and antiresorptive therapies have been applied to maintain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs) are employed to treat patients suffering from delayed fracture healing and nonunions. Although PEMFs stimulate osteoblastogenesis, suppress osteoclastogenesis, and influence the activity of bone marrow mesenchymal stem cells (BMSCs) and osteocytes, ultimately leading to retention of bone mass and strength. However, whether PEMFs could be taken into clinical use to treat OP is still unknown. Furthermore, the deeper signaling pathways underlying the way in which PEMFs influence OP remain unclear.

"Dangerous duo": Chronic nicotine exposure intensifies diabetes mellitus-related deterioration in bone microstructure - An experimental study in rats

AIMS

Bony complications of diabetes mellitus (DM) are still insufficiently understood. Our aims were to analyze the individual and combined effects of chronic hyperglycemia and nicotine exposure on the femoral trabecular and cortical microarchitecture on a rat experimental model.

MAIN METHODS

The micro-computed tomography based bone microstructural evaluation was performed on male Wistar rats divided into four groups: control (n = 7), experimentally-induced DM (n = 8), chronically exposed to nicotine (n = 9) and the DM group exposed chronically to nicotine (n = 9).

KEY FINDINGS

Chronic hyperglycemia caused mild trabecular deterioration; yet, the combination of hyperglycemia and nicotine exposure showed more deleterious effects on the trabecular bone. Namely, the DM + nicotine group had significantly lower bone volume fraction, fewer and more rod-like shaped trabeculae, along with higher trabecular separation and lower connectivity than the control group (p < 0.05). Nicotine alone did not show any significant deterioration compared to the control group. DM and DM + nicotine groups had lower cortical porosity than control and nicotine groups (p < 0.05). Cortical thickness did not show any significant intergroup differences, whereas bone perimeter and the mean polar moment of inertia were reduced in DM + nicotine group.

SIGNIFICANCE

Mild effects of chronic hyperglycemia on bone structure were accentuated by the chronic nicotine exposure, although nicotine alone did not cause any significant bone changes. That suggests a synergistic effect of hyperglycemia and nicotine on bone deterioration and increased propensity to fracture. Indeed, better understanding of risk factors driving bone structural deterioration is a precondition to limit the complications associated with DM.

Pulsed electromagnetic fields prevented the decrease of bone formation in hindlimb-suspended rats by activating sAC/cAMP/PKA/CREB signaling pathway

Microgravity is one of the main threats to the health of astronauts. Pulsed electromagnetic fields (PEMFs) have been considered as one of the potential countermeasures for bone loss induced by space flight. However, the optimal therapeutic parameters of PEMFs have not been obtained and the action mechanism is still largely unknown. In this study, a set of optimal therapeutic parameters for PEMFs (50 Hz, 0.6 mT 50% duty cycle and 90 min/day) selected based on high-throughput screening with cultured osteoblasts was used to prevent bone loss in rats induced by hindlimb suspension, a commonly accepted animal model to simulate the space environment. It was found that hindlimb suspension for 4 weeks led to significant decreases in femoral and vertebral bone mineral density (BMD) and their maximal loads, severe deterioration in bone micro-structure, and decreases in levels of bone formation markers and increases in bone resorption markers. PEMF treatment prevented about 50% of the decreased BMD and maximal loads, preserved the microstructure of cancellous bone and thickness of cortical bone, and inhibited decreases in bone formation markers. Histological analyses revealed that PEMFs significantly alleviated the reduction in osteoblast number and inhibited the increase in adipocyte number in the bone marrow. PEMFs also blocked decreases in serum levels of parathyroid hormone and its downstream signal molecule cAMP, and maintained the phosphorylation levels of protein kinase A (PKA) and cAMP response element-binding protein (CREB). The expression level of soluble adenylyl cyclases (sAC) was also maintained. It therefore can be concluded that PEMFs partially prevented the bone loss induced by weightless environment by maintaining bone formation through signaling of the sAC/cAMP/PKA/CREB pathway. Bioelectromagnetics. 39:569-584, 2018. © 2018 Wiley Periodicals, Inc.

Moderate-intensity 4mT static magnetic fields prevent bone architectural deterioration and strength reduction by stimulating bone formation in streptozotocin-treated diabetic rats

Type 1 diabetes mellitus (T1DM) has been associated with deterioration of bone microarchitecture and strength, resulting in increased fracture risk. Substantial studies have revealed the capacity of moderate-intensity static magnetic fields (SMF) on promoting osteoblastogenesis in vitro and stimulating bone growth and bone regeneration in vivo, whereas it is unknown whether SMF can resist T1DM-associated osteopenia/osteoporosis. We herein investigated the potential effects of whole-body SMF exposure with 4mT on bone loss in streptozotocin-induced T1DM rats. We found that SMF exposure for 16weeks inhibited architectural deterioration of trabecular bone and cortical bone and mechanical strength reduction in T1DM rats, as evidenced by the MicroCT and 3-point bending findings. Our serum biochemical, bone histomorphometric and PCR results revealed that SMF induced higher serum osteocalcin, mineral apposition rate and osteoblast number of trabecular bone, and higher skeletal osteocalcin, BMP2 and Runx2 gene expression in T1DM rats, whereas SMF showed no significant alteration in serum CTX, skeletal osteoclast number, or osteoclastogenesis-related RANKL-RANK signaling gene expression. Together, our findings suggest that moderate SMF prevented bone architectural deterioration and strength reduction by inhibiting the reduction of bone formation in T1DM rats, and indicate that SMF might become a promising biophysical countermeasure for T1DM-related osteopenia/osteoporosis.

Low-1 level mechanical vibration improves bone microstructure, tissue mechanical properties and porous titanium implant osseointegration by promoting anabolic response in type 1 diabetic rabbits

Type 1 diabetes mellitus (T1DM) is associated with reduced bone mass, increased fracture risk, and impaired bone defect regeneration potential. These skeletal complications are becoming important clinical challenges due to the rapidly increasing T1DM population, which necessitates developing effective treatment for T1DM-associated osteopenia/osteoporosis and bone trauma. This study aims to investigate the effects of whole-body vibration (WBV), an easy and non-invasive biophysical method, on bone microstructure, tissue-level mechanical properties and porous titanium (pTi) osseointegration in alloxan-diabetic rabbits. Six non-diabetic and twelve alloxan-treated diabetic rabbits were equally assigned to the Control, DM, and DM with WBV stimulation (WBV) groups. A cylindrical drill-hole defect was established on the left femoral lateral condyle of all rabbits and filled with a novel non-toxic Ti2448 pTi. Rabbits in the WBV group were exposed to 1h/day WBV (0.3g, 30Hz) for 8weeks. After sacrifice, the left femoral condyles were harvested for histological, histomorphometric and nanoindentation analyses. The femoral sample with 2-cm height above the defect was used for qRT-PCR analysis. The right distal femora were scanned with μCT. We found that all alloxan-treated rabbits exhibited hyperglycemia throughout the experimental period. WBV inhibited the deterioration of cancellous and cortical bone architecture and tissue-level mechanical properties via μCT, histological and nanoindentation examinations. T1DM-induced reduction of bone formation was inhibited by WBV, as evidenced by elevated serum OCN and increased mineral apposition rate (MAR), whereas no alteration was observed in bone resorption marker TRACP5b. WBV also stimulated more adequate ingrowths of mineralized bone tissue into pTi pore spaces, and improved peri-implant bone tissue-level mechanical properties and MAR in T1DM bone defects. WBV mitigated the reductions in femoral BMP2, OCN, Wnt3a, Lrp6, and β-catenin and inhibited Sost mRNA expression but did not alter RANKL or RANK gene expression in T1DM rabbits. Our findings demonstrated that WBV improved bone architecture, tissue-level mechanical properties, and pTi osseointegration by promoting canonical Wnt signaling-mediated skeletal anabolic response. This study not only advances our understanding of T1DM skeletal sensitivity in response to external mechanical cues but also offers new treatment alternatives for T1DM-associated osteopenia/osteoporosis and osseous defects in an economic and highly efficient manner.

Effects of low-intensity pulsed electromagnetic fields on bone microarchitecture, mechanical strength and bone turnover in type 2 diabetic db/db mice

Type 2 diabetic patients have impaired bone quality, leading to increased fracture risk. Substantial evidence demonstrates that pulsed electromagnetic fields (PEMF) could resist osteopenia/osteoporosis induced by estrogen deficiency and disuse. However, the effects of PEMF on osteopenia/osteoporosis associated with diabetes, especially for more prevalent type 2 diabetes, remain poorly understood. We herein investigated the skeletal effects and mechanisms of PEMF (15 Hz, 20 Gs) on leptin receptor-deficient db/db mice with typical type 2 diabetic symptoms. Our µCT results showed that 12-week PEMF exposure significantly improved both cancellous and cortical bone microarchitecture in db/db mice. Three-point bending and biomechanical indentation testing demonstrated that PEMF improved whole-bone structural properties and tissue-level material properties in db/db mice. PEMF significantly promoted bone formation in db/db mice evidenced by increased serum osteocalcin and bone mineral apposition rate, whereas PEMF exerted no observable alteration in bone resorption. Real-time PCR showed that PEMF upregulated tibial gene expression of osteoblastogenesis-related of canonical Wnt/β-catenin signaling but not osteoclastogenesis-related RANKL-RANK signaling in db/db mice. Our findings demonstrate that PEMF improved bone quantity and quality with obvious anabolic activities in db/db mice, and imply that PEMF might become a clinically applicable treatment modality for improving bone quality in type 2 diabetic patients.

Effects of pulsed electromagnetic fields on postmenopausal osteoporosis

Postmenopausal osteoporosis (PMOP) is considered to be a well-defined subject that has caused high morbidity and mortality. In elderly women diagnosed with PMOP, low bone mass and fragile bone strength have been proven to significantly increase risk of fragility fractures. Currently, various anabolic and anti-resorptive therapies have been employed in an attempt to retain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs), first applied in treating patients with delayed fracture healing and nonunions, may turn out to be another potential and effective therapy for PMOP. PEMFs can enhance osteoblastogenesis and inhibit osteoclastogenesis, thus contributing to an increase in bone mass and strength. However, accurate mechanisms of the positive effects of PEMFs on PMOP remain to be further elucidated. This review attempts to summarize recent advances of PEMFs in treating PMOP based on clinical trials, and animal and cellular studies. Possible mechanisms are also introduced, and the future possibility of application of PEMFs on PMOP are further explored and discussed. Bioelectromagnetics. 38:406-424, 2017. © 2017 Wiley Periodicals, Inc.

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

Pulsed electromagnetic fields (PEMFs) have been documented to promote bone fracture healing in nonunions and increase lumbar spinal fusion rates. However, the molecular mechanisms by which PEMF stimulates differentiation of human bone marrow stromal cells (hBMSCs) into osteoblasts are not well understood. In this study the PEMF effects on hBMSCs were studied by microarray analysis. PEMF stimulation of hBMSCs' cell numbers mainly affected genes of cell cycle regulation, cell structure, and growth receptors or kinase pathways. In the differentiation and mineralization stages, PEMF regulated preosteoblast gene expression and notably, the transforming growth factor-beta (TGF-β) signaling pathway and microRNA 21 (miR21) were most highly regulated. PEMF stimulated activation of Smad2 and miR21-5p expression in differentiated osteoblasts, and TGF-β signaling was essential for PEMF stimulation of alkaline phosphatase mRNA expression. Smad7, an antagonist of the TGF-β signaling pathway, was found to be miR21-5p's putative target gene and PEMF caused a decrease in Smad7 expression. Expression of Runx2 was increased by PEMF treatment and the miR21-5p inhibitor prevented the PEMF stimulation of Runx2 expression in differentiating cells. Thus, PEMF could mediate its effects on bone metabolism by activation of the TGF-β signaling pathway and stimulation of expression of miR21-5p in hBMSCs.

Pulsed electromagnetic fields promote osteogenesis and osseointegration of porous titanium implants in bone defect repair through a Wnt/β-catenin signaling-associated mechanism

Treatment of osseous defects remains a formidable clinical challenge. Porous titanium alloys (pTi) have been emerging as ideal endosseous implants due to the excellent biocompatibility and structural properties, whereas inadequate osseointegration poses risks for unreliable long-term implant stability. Substantial evidence indicates that pulsed electromagnetic fields (PEMF), as a safe noninvasive method, inhibit osteopenia/osteoporosis experimentally and clinically. We herein investigated the efficiency and potential mechanisms of PEMF on osteogenesis and osseointegration of pTi in vitro and in vivo. We demonstrate that PEMF enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton for in vitro osteoblasts seeded in pTi. PEMF promoted gene expressions in Runx2, OSX, COL-1 and Wnt/β-catenin signaling. PEMF-stimulated group exhibited higher Runx2, Wnt1, Lrp6 and β-catenin protein expressions. In vivo results via μCT and histomorphometry show that 6-week and 12-week PEMF promoted osteogenesis, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defect. PEMF promoted femoral gene expressions of Runx2, BMP2, OCN and Wnt/β-catenin signaling. Together, we demonstrate that PEMF improve osteogenesis and osseointegration of pTi by promoting skeletal anabolic activities through a Wnt/β-catenin signaling-associated mechanism. PEMF might become a promising biophysical modality for enhancing the repair efficiency and quality of pTi in bone defect.

Effects of electromagnetic fields on osteoporosis: A systematic literature review

Electromagnetic fields (EMFs) as a safe, effective and noninvasive treatment have been researched and used for many years in orthopedics, and the common use clinically is to promote fracture healing. The effects of EMFs on osteoporosis have not been well concerned. The balance between osteoblast and osteoclast activity as well as the balance between osteogenic differentiation and adipogenic differentiation of bone marrow mesenchymal stem cells plays an important role in the process of osteoporosis. A number of recent reports suggest that EMFs have a positive impact on the balances. In this review, we discuss the recent advances of EMFs in the treatment of osteoporosis from basic research to clinical study and introduce the possible mechanism. In addition, we presented future perspectives of application of EMFs for osteoporosis.

Pulsed electromagnetic fields promote in vitro osteoblastogenesis through a Wnt/β-catenin signaling-associated mechanism

Substantial evidence indicates that pulsed electromagnetic fields (PEMF) could accelerate fracture healing and enhance bone mass, whereas the unclear mechanism by which PEMF stimulation promotes osteogenesis limits its extensive clinical application. In the present study, effects and potential molecular signaling mechanisms of PEMF on in vitro osteoblasts were systematically investigated. Osteoblast-like MC3T3-E1 cells were exposed to PEMF burst (0.5, 1, 2, or 6 h/day) with 15.38 Hz at various intensities (5 Gs (0.5 mT), 10 Gs (1 mT), or 20 Gs (2 mT)) for 3 consecutive days. PEMF stimulation at 20 Gs (2 mT) for 2 h/day exhibited most prominent promotive effects on osteoblastic proliferation via Cell Counting kit-8 analyses. PEMF exposure induced well-organized cytoskeleton, and promoted formation of extracellular matrix mineralization nodules. Significantly increased proliferation-related gene expressions at the proliferation phase were observed after PEMF stimulation, including Ccnd 1 and Ccne 1. PEMF resulted in significantly increased gene and protein expressions of alkaline phosphatase and osteocalcin at the differentiation phase of osteoblasts rather than the proliferation phase via quantitative reverse transcription polymerase chain reaction and Western blotting analyses. Moreover, PEMF upregulated gene and protein expressions of collagen type 1, Runt-related transcription factor 2 and Wnt/β-catenin signaling (Wnt1, Lrp6, and β-catenin) at proliferation and differentiation phases. Together, our present findings highlight that PEMF stimulated osteoblastic functions through a Wnt/β-catenin signaling-associated mechanism and, hence, regulates downstream osteogenesis-associated gene/protein expressions. Bioelectromagnetics. 37:152-162, 2016. © 2016 Wiley Periodicals, Inc.

Effect of Pulsed Electromagnetic Field on Bone Formation and Lipid Metabolism of Glucocorticoid-Induced Osteoporosis Rats through Canonical Wnt Signaling Pathway

Pulsed electromagnetic field (PEMF) has been suggested as a promising method alternative to drug-based therapies for treating osteoporosis (OP), but the role of PEMF in GIOP animal models still remains unknown. This study was performed to investigate the effect of PEMF on bone formation and lipid metabolism and further explored the several important components and targets of canonical Wnt signaling pathway in GIOP rats. After 12 weeks of intervention, bone mineral density (BMD) level of the whole body increased significantly, serum lipid levels decreased significantly, and trabeculae were thicker in GIOP rats of PEMF group. PEMF stimulation upregulated the mRNA and protein expression of Wnt10b, LRP5, β-catenin, OPG, and Runx2 and downregulated Axin2, PPAR-γ, C/EBPα, FABP4, and Dkk-1. The results of this study suggested that PEMF stimulation can prevent bone loss and improve lipid metabolism disorders in GIOP rats. Canonical Wnt signaling pathway plays an important role in bone formation and lipid metabolism during PEMF stimulation.

Effects of extremely low frequency pulsed magnetic fields on diabetic nephropathy in streptozotocin-treated rats

Background

Extremely low frequency pulsed magnetic fields (ELFPMF) have been shown to induce Faraday currents and measurable effects on biological systems. A kind of very high frequency electromagnetic field was reported that it improved the symptoms of diabetic nephropathy (DN) which is a major complication of diabetes. However, few studies have examined the effects of ELFPMF DN at the present. The present study was designed to investigate the effects of ELFPMF on DN in streptozotocin (STZ)–induced type 1 diabetic rats.

Methods

Adult male SD rats were randomly divided into three weight-matched groups: Control (non-diabetic rats without DN), DN + ELFPMF (diabetic rats with DN exposed to ELFPMF, 8 h/days, 6 weeks) and DN (diabetic rats with DN exposed to sham ELFPMF). Renal morphology was examined by light and electron microscopy, vascular endothelial growth factor (VEGF)-A and connective tissue growth factor (CTGF) were measured by enzyme linked immune sorbent assay.

Results

After 6 weeks’ ELFPMF exposure, alterations of hyperglycemia and weight loss in STZ-treated rats with DN were not found, while both positive and negative effects of ELFPMF on the development of DN in diabetic rats were observed. The positive one was that ELFPMF exposure attenuated the pathological alterations in renal structure observed in STZ-treated rats with DN, which were demonstrated by slighter glomerular and tubule-interstitial lesions examined by light microscopy and slighter damage to glomerular basement membrane and podocyte foot processes examined by electron microscopy. And then, the negative one was that ELFPMF stimulation statistically significantly decreased renal expression of VEGF-A and statistically significantly increased renal expression of CTGF in diabetic rats with DN, which might partially aggravate the symptoms of DN.

Conclusion

Both positive and negative effects of ELFPMF on the development of DN in diabetic rats were observed. The positive effect induced by ELFPMF might play a dominant role in the procession of DN in diabetic rats, and it is suggested that the positive effect should be derived from the correction of pathogenic diabetes-induced mediators.

Pentoxifylline and electromagnetic field improved bone fracture healing in rats

Background

The aim of this study was to evaluate the effects of a phosphodiesterase inhibitor pentoxifylline (PTX), electromagnetic fields (EMFs), and a mixture of both materials on bone fracture healing in a rat model.

Materials and methods

Eighty male Wistar rats were randomly divided into four groups: Group A, femur fracture model with no treatment; Group B, femur fracture model treated with PTX 50 mg/kg/day intraperitoneal injection; Group C, femur fracture model treated with EMF 1.5±0.2 Mt/50 Hz/6 hours/day; and Group D, femur fracture model treated with PTX 50 mg/kg/day intraperitoneal injection and EMF 1.5±0.2 Mt/50 Hz/6 hours/day.

Results

Bone fracture healing was significantly better in Group B and Group C compared to Group A (P<0.05), but Group D did not show better bone fracture healing than Group A (P>0.05).

Conclusion

It can be concluded that both a specific EMF and PTX had a positive effect on bone fracture healing but when used in combination, may not be beneficial.

Chronic Exposure to Static Magnetic Fields from Magnetic Resonance Imaging Devices Deserves Screening for Osteoporosis and Vitamin D Levels: A Rat Model

Technicians often receive chronic magnetic exposures from magnetic resonance imaging (MRI) devices, mainly due to static magnetic fields (SMFs). Here, we ascertain the biological effects of chronic exposure to SMFs from MRI devices on the bone quality using rats exposed to SMFs in MRI examining rooms. Eighteen Wistar albino male rats were randomly assigned to SMF exposure (A), sham (B), and control (C) groups. Group A rats were positioned within 50 centimeters of the bore of the magnet of 1.5 T MRI machine during the nighttime for 8 weeks. We collected blood samples for biochemical analysis, and bone tissue samples for electron microscopic and histological analysis. The mean vitamin D level in Group A was lower than in the other groups (p = 0.002). The mean cortical thickness, the mean trabecular wall thickness, and number of trabeculae per 1 mm² were significantly lower in Group A (p = 0.003). TUNEL assay revealed that apoptosis of osteocytes were significantly greater in Group A than the other groups (p = 0.005). The effect of SMFs in chronic exposure is related to movement within the magnetic field that induces low-frequency fields within the tissues. These fields can exceed the exposure limits necessary to deteriorate bone microstructure and vitamin D metabolism.

Pulsed electromagnetic fields inhibit bone loss in streptozotocin-induced diabetic rats

Evidences have shown that pulsed electromagnetic fields (PEMFs) can partially prevent bone loss in streptozotocin (STZ)-induced diabetic rats. However, the precise mechanisms accounting for these favorable effects are unclear. This study aimed to investigate the effects of PEMFs on bone mass and receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG) and Wnt/β-catenin signaling pathway in STZ rats. Thirty 3-month-old Sprague Dawley rats were randomly divided into the following three groups (n = 10): control group (injection of saline vehicle), DM group (injection of STZ), and PEMFs group (injection of STZ + PEMFs exposure). One week following injection of STZ, rats in the PEMFs group were subject to PEMFs stimulus for 40 min/day, 5 days/week, and lasted for 12 weeks. After 12 week intervention, the results showed that PEMFs increased serum bone-specific alkaline phosphatase level and bone mineral density, and inhibited deterioration of bone microarchitecture and strength in STZ rats. Furthermore, PEMFs up-regulated the mRNA expressions of low-density lipoprotein receptor-related protein 5, β-catenin and runt-related gene 2 (Runx2), and down-regulated dickkopf1 in STZ rats. However, mRNA expressions of RANKL and OPG were not affected by PEMFs. PEMFs can prevent the diabetes-induced bone loss and reverse the deterioration of bone microarchitecture and strength by restoring Runx2 expression through regulation of Wnt/β-catenin signaling, regardless of its no glucose lowering effect.

Pulsed electromagnetic fields partially preserve bone mass, microarchitecture, and strength by promoting bone formation in hindlimb-suspended rats

A large body of evidence indicates that pulsed electromagnetic fields (PEMF), as a safe and noninvasive method, could promote in vivo and in vitro osteogenesis. Thus far, the effects and underlying mechanisms of PEMF on disuse osteopenia and/or osteoporosis remain poorly understood. Herein, the efficiency of PEMF on osteoporotic bone microarchitecture, bone strength, and bone metabolism, together with its associated signaling pathway mechanism, was systematically investigated in hindlimb-unloaded (HU) rats. Thirty young mature (3-month-old), male Sprague-Dawley rats were equally assigned to control, HU, and HU + PEMF groups. The HU + PEMF group was subjected to daily 2-hour PEMF exposure at 15 Hz, 2.4 mT. After 4 weeks, micro-computed tomography (µCT) results showed that PEMF ameliorated the deterioration of trabecular and cortical bone microarchitecture. Three-point bending test showed that PEMF mitigated HU-induced reduction in femoral mechanical properties, including maximum load, stiffness, and elastic modulus. Moreover, PEMF increased serum bone formation markers, including osteocalcin (OC) and N-terminal propeptide of type 1 procollagen (P1NP); nevertheless, PEMF exerted minor inhibitory effects on bone resorption markers, including C-terminal crosslinked telopeptides of type I collagen (CTX-I) and tartrate-resistant acid phosphatase 5b (TRAcP5b). Bone histomorphometric analysis demonstrated that PEMF increased mineral apposition rate, bone formation rate, and osteoblast numbers in cancellous bone, but PEMF caused no obvious changes on osteoclast numbers. Real-time PCR showed that PEMF promoted tibial gene expressions of Wnt1, LRP5, β-catenin, OPG, and OC, but did not alter RANKL, RANK, or Sost mRNA levels. Moreover, the inhibitory effects of PEMF on disuse-induced osteopenia were further confirmed in 8-month-old mature adult HU rats. Together, these results demonstrate that PEMF alleviated disuse-induced bone loss by promoting skeletal anabolic activities, and imply that PEMF might become a potential biophysical treatment modality for disuse osteoporosis.

Moderate-intensity rotating magnetic fields do not affect bone quality and bone remodeling in hindlimb suspended rats

Abundant evidence has substantiated the positive effects of pulsed electromagnetic fields (PEMF) and static magnetic fields (SMF) on inhibiting osteopenia and promoting fracture healing. However, the osteogenic potential of rotating magnetic fields (RMF), another common electromagnetic application modality, remains poorly characterized thus far, although numerous commercial RMF treatment devices have been available on the market. Herein the impacts of RMF on osteoporotic bone microarchitecture, bone strength and bone metabolism were systematically investigated in hindlimb-unloaded (HU) rats. Thirty two 3-month-old male Sprague-Dawley rats were randomly assigned to the Control (n = 10), HU (n = 10) and HU with RMF exposure (HU+RMF, n = 12) groups. Rats in the HU+RMF group were subjected to daily 2-hour exposure to moderate-intensity RMF (ranging from 0.60 T to 0.38 T) at 7 Hz for 4 weeks. HU caused significant decreases in body mass and soleus muscle mass of rats, which were not obviously altered by RMF. Three-point bending test showed that the mechanical properties of femurs in HU rats, including maximum load, stiffness, energy absorption and elastic modulus were not markedly affected by RMF. µCT analysis demonstrated that 4-week RMF did not significantly prevent HU-induced deterioration of femoral trabecular and cortical bone microarchitecture. Serum biochemical analysis showed that RMF did not significantly change HU-induced decrease in serum bone formation markers and increase in bone resorption markers. Bone histomorphometric analysis further confirmed that RMF showed no impacts on bone remodeling in HU rats, as evidenced by unchanged mineral apposition rate, bone formation rate, osteoblast numbers and osteoclast numbers in cancellous bone. Together, our findings reveal that RMF do not significantly affect bone microstructure, bone mechanical strength and bone remodeling in HU-induced disuse osteoporotic rats. Our study indicates potentially obvious waveform-dependent effects of electromagnetic fields-stimulated osteogenesis, suggesting that RMF, at least in the present form, might not be an optimal modality for inhibiting disuse osteopenia/osteoporosis.

Evaluation of stability of surface-treated mini-implants in diabetic rabbits

Introduction. The purpose of this study was to investigate effects of surface treatment of mini-implants in diabetes-induced rabbits by comparing osseointegration around mini-implants. Methods. Twelve New Zealand white rabbits were divided into two groups (alloxan-induced diabetic group and control group). A total of 48 mini-implants were placed after four weeks of diabetic induction. 24 mini-implants were surface-treated with SLA (sandblasted with large grit, and acid etched) and the remaining 24 mini-implants had smooth surfaces. Four weeks after placement, 32 mini-implants were removed from 4 control and 4 diabetic rabbits. Insertion and removal torques were measured. The remaining 16 mini-implants from the two groups were histomorphometrically analyzed. Results. Maximum insertion torque showed no difference between diabetic and control groups, but total insertion energy was higher in control group. In surface-treated mini-implants, maximum removal torque was higher in both diabetic and control groups. Bone-implant contact (BIC) was increased in the control group when compared to the diabetic group. Surface-treated group had higher BIC than smooth surface group in both control and diabetic groups. However, there was no significantly statistical difference. Conclusions. Type 1 diabetes mellitus and surface treatment method of mini-implant affected primary stability of mini-implants. In addition, the use of orthodontic mini-implants in a diabetic patient is likely to show results similar to the healthy patient.

Effects of short-term resistance training and pulsed electromagnetic fields on bone metabolism and joint function in severe haemophilia A patients with osteoporosis: a randomized controlled trial

OBJECTIVES

To assess the effects of short-term resistance training and pulsed electromagnetic fields on bone metabolism and joint function in patients with haemophilia with osteoporosis.

DESIGN

A randomized, controlled, patient and blood sample assessor-blinded, six-week trial, three times weekly.

SETTING

Hospital outpatients with severe haemophilia A and osteoporosis.

SUBJECTS

Forty-eight patients were randomly assigned to resistance training (RT, n = 13), combined resistance training with pulsed electromagnetic fields (RTPEMF, n = 12), pulsed electromagnetic fields (PEMF, n = 11) and control (n = 12) groups.

INTERVENTION

The RT group received 30-40 minutes of resistance exercises and placebo pulsed electromagnetic fields. The RTPEMF group received the same exercises with lower repetition and 30 minutes of pulsed electromagnetic fields. The PEMF group was exposed to 60 minutes of pulsed electromagnetic fields (30 Hz and 40 Gauss).

MAIN MEASURES

Bone-specific alkaline phosphatase, N-terminal telopeptide of type 1 collagen, and joint function, using the modified Colorado Questionnaire, were measured before and after the programme.

RESULTS

The absolute change of bone-specific alkaline phosphatase was significant in the RT and RTPEMF groups compared with the control group (25.41 ± 14.40, 15.09 ± 5.51, and -4.73 ± 2.93 U/L, respectively). The absolute changes in the total score for joint function were significant for knees, ankles, and elbows in the RT group (9.2 ± 1.38, 5.1 ± 0.5, and 3.2 ± 0.8, respectively) and the RTPEMF group (7.7 ± 1.0, 3.3 ± 0.6, and 2.5 ± 0.7, respectively) compared to the PEMF and control groups. This value was significant for knee joints in the PEMF group compared to the control group (3.4 ± 0.5 and 0.66 ± 0.4, respectively).

CONCLUSIONS

Resistance training is effective for improving bone formation and joint function in severe haemophilia A patients with osteoporosis.

Pulsed electromagnetic fields improve bone microstructure and strength in ovariectomized rats through a Wnt/Lrp5/β-catenin signaling-associated mechanism

Growing evidence has demonstrated that pulsed electromagnetic field (PEMF), as an alternative noninvasive method, could promote remarkable in vivo and in vitro osteogenesis. However, the exact mechanism of PEMF on osteopenia/osteoporosis is still poorly understood, which further limits the extensive clinical application of PEMF. In the present study, the efficiency of PEMF on osteoporotic bone microarchitecture and bone quality together with its associated signaling pathway mechanisms was systematically investigated in ovariectomized (OVX) rats. Thirty rats were equally assigned to the Control, OVX and OVX+PEMF groups. The OVX+PEMF group was subjected to daily 8-hour PEMF exposure with 15 Hz, 2.4 mT (peak value). After 10 weeks, the OVX+PEMF group exhibited significantly improved bone mass and bone architecture, evidenced by increased BMD, Tb.N, Tb.Th and BV/TV, and suppressed Tb.Sp and SMI levels in the MicroCT analysis. Three-point bending test suggests that PEMF attenuated the biomechanical strength deterioration of the OVX rat femora, evidenced by increased maximum load and elastic modulus. RT-PCR analysis demonstrated that PEMF exposure significantly promoted the overall gene expressions of Wnt1, LRP5 and β-catenin in the canonical Wnt signaling, but did not exhibit obvious impact on either RANKL or RANK gene expressions. Together, our present findings highlight that PEMF attenuated OVX-induced deterioration of bone microarchitecture and strength in rats by promoting the activation of Wnt/LRP5/β-catenin signaling rather than by inhibiting RANKL-RANK signaling. This study enriches our basic knowledge to the osteogenetic activity of PEMF, and may lead to more efficient and scientific clinical application of PEMF in inhibiting osteopenia/osteoporosis.

Yeast-incorporated gallium attenuates glucocorticoid-induced bone loss in rats by inhibition of bone resorption

Glucocorticoids (GC) are potent anti-inflammatory agents and widely used for the treatment of many immune-mediated and inflammatory diseases, whereas GC-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis and significantly increases the patients' morbidity and mortality. GIOP is characterized as diminished osteogenesis and accelerated bone resorption. Yeast-incorporated gallium (YG) as an organic compound not only reduces elements-associated toxicity, but also maintains its therapeutic effect on improving bone loss or promoting fracture healing in ovariectomized female rats. The aim of this study was to examine whether YG could prevent GC-induced bone loss. Five-month-old male Sprague-Dawley rats were randomly divided into three groups (n = 6): two groups were administered dexamethasone (0.1 mg/kg/day) or vehicle (PBS) subcutaneously for 5 weeks; one other group was received dexamethasone subcutaneously and YG (120 μg/kg/day) orally. Trabecular bone microarchitectural parameters, bone mineral density (BMD), bone strength, body weight, and serum biochemical markers of bone resorption and formation were examined. Compared to the GC alone group, treatment with YG not only prevented microarchitectural deterioration of trabecular bone volume relative to tissue volume, trabecular number, and trabecular separation, but also significantly improved BMD, mechanical strength, and body weight in GC-treated rats. Moreover, YG decreased tartrate-resistant acid phosphatase 5b level but failed to change alkaline phosphatase level in GC-treated rats. This is the first study to show that YG prominently attenuates bone loss and microarchitectural deterioration and inhibits the increased bone resorption in GIOP. It implies that YG might be an alternative therapy for prevention of GC-induced bone loss in humans.