Effects of pulsed electromagnetic fields on cartilage apoptosis signalling pathways in ovariectomised rats

Effects of the combination of pulsed electromagnetic field with progressive resistance exercise on knee osteoarthritis: A randomized controlled trial

BACKGROUND

Knee osteoarthritis (OA) is a common and disabling disease among the elderly population. The optimal conservative treatment for knee OA is not well established.

OBJECTIVE

This study aimed to assess the effectiveness of pulsed electromagnetic field (PEMF) combined with progressive resistance exercise (PRE) in improving physical function and pain in patients with knee OA.

METHODS

Thirty-four patients with knee OA (17 in each group) participated in a single-blind randomized control study. Patients were randomly assigned to receive 24 sessions of either combined PEMF and PRE (treatment group) or PRE only (control group). Patients were evaluated at pre-treatment, post-treatment (2 months), and at 3-month and 6-month follow-ups using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Numeric Pain Rating Scale (NPRS); walking speed and 5-times chair stand test. Mixed ANOVA was used for statistical analysis with Bonferroni adjustments.

RESULTS

There was no significant group-by-time interaction for any outcome (P> 0.05). However, both groups scored significantly higher on the NPRS and KOOS at post-treatment, 3-, and 6-month follow-up compared to their baseline. Further, both groups completed the 5-times chair stand test and walking speed test with significantly less time at all post-treatment time points than the pre-treatment. None of the study outcomes (NPRS, KOOS, walking speed, and 5 times chair stand) were significantly different between groups at any of the time points.

CONCLUSION

Both treatment options, PRE only versus PRE with PEMF, were equally effective in decreasing pain and improving physical function in patients with knee OA. This would suggest that the optimal parameters for PEMF that may show beneficial effects for knee OA when added to PRE training need to be determined.

Pulsed Electromagnetic Field Attenuates Osteoarthritis Progression in a Murine Destabilization-Induced Model through Inhibition of TNF-α and IL-6 Signaling

OBJECTIVE

To investigate the anti-inflammatory effects and mechanisms of pulsed electromagnetic field (PEMF) in the treatment of osteoarthritis (OA) in the destabilization of the medial meniscus (DMM) mice.

DESIGN

Ten-week-old male wild-type (WT), interleukin (IL)-6-/- and tumor necrosis factor (TNF)-α-/- mice undergoing DMM surgery were randomly divided into 2 groups (n = 10 each): mice with PEMF exposure and mice with sham PEMF exposure. PEMF (75 Hz, 3.8 mT, 1 h/day) or sham PEMF was applied for 4 weeks. Pain behavior of mice, histological assessment of cartilage and synovium, micro-CT (computed tomography) analysis of bone, real-time polymerase chain reaction, and immunohistochemical staining of cartilage were performed.

RESULTS

After DMM surgery, PEMF had a beneficial effect on pain, cartilage degeneration, synovitis, and trabecular bone microarchitecture in WT mice; these protective effects were reduced in IL-6-/- and TNF-α-/- mice. In addition, PEMF downregulated IL-6 and TNF-α expression in cartilage. PEMF also ameliorated cartilage matrix, chondrocyte apoptosis, and autophagy, while deletion of IL-6 or TNF-α suppressed the effects.

CONCLUSIONS

PEMF attenuates structural and functional progression of OA through inhibition of TNF-α and IL-6 signaling. The protective effects of PEMF on chondrocyte apoptosis and autophagy are regulated by TNF-α and IL-6 signaling.

Effects of electromagnetic fields on osteoarthritis

Osteoarthritis (OA), characterized by joint malfunction and chronic disability, is the most common form of arthritis. The pathogenesis of OA is unclear, yet studies have shown that it is due to an imbalance between the synthesis and decomposition of chondrocytes, cell matrices and subchondral bone, which leads to the degeneration of articular cartilage. Currently, there are many therapies that can be used to treat OA, including the use of pulsed electromagnetic fields (PEMFs). PEMFs stimulate proliferation of chondrocytes and exert a protective effect on the catabolic environment. Furthermore, this technique is beneficial for subchondral trabecular bone microarchitecture and the prevention of subchondral bone loss, ultimately blocking the progression of OA. However, it is still unknown whether PEMFs could be used to treat OA in the clinic. Furthermore, the deeper signaling pathways underlying the mechanism by which PEMFs influence OA remain unclear.

Influence of High Frequency Electromagnetic Fields Produced by Antennas for Mobile Communication on the Structure of the Pancreas in Rats: Histological and Unbiased Stereological Analysis

The emission of high frequency electromagnetic fields (HF EMF) produced by antennas for mobile communications has been controversially alleged to have adverse health effects. The aim of our work was to examine whether there are effects on living organisms from HF EMF produced by mobile communication antennas. In this experiment Wistar strain rats were exposed to HF EMF with the following characteristics: 1.9 GHz frequency, 0.24 A/m intensity, electric field strength of 4.79 V/m, and SAR (specific absorption rate) value of 2.0 W/m2. Exposure time was 7 hours per day, 5 days per week, over the course of sixty days. This experiment was conducted on a total of 30 male rats divided randomly into two equal groups: one group of animals was exposed to GSM fields (Global System of antennas for Mobile Communications) as described above whereas the other group of animals was not exposed to any GSM fields. In our study, results show that the quantity, diameter and numerical density of the islets of Langerhans in the pancreatic tissue increased in rats exposed to HF EMF compared to the unexposed group. The volume density, number and numerical density of pancreatic cells also changed in rats that were exposed to the HF EMF compared to the unexposed group. Our study shows a change in the stereological and histological parameters of rat pancreatic tissue due to the effects of HF EM fields produced by antennas for mobile communication.

Pulsed electromagnetic field induces Ca2+-dependent osteoblastogenesis in C3H10T1/2 mesenchymal cells through the Wnt-Ca2+/Wnt-β-catenin signaling pathway

Pulsed electromagnetic fields (PEMFs) are effective in healing fractures and improving osteoporosis. However, their effect on mesenchymal cells remains largely unknown. In this study, the effects of PEMF on osteoblastogenesis and its underlying molecular signaling mechanisms were systematically investigated in C3H10T1/2 cells. C3H10T1/2 mesenchymal cells were exposed to 30-Hz PEMF bursts at various intensities for 3 consecutive days. The optimal PEMF exposure (30 Hz, 1 mT, 2 h/day) was applied in subsequent experiments. Our results suggest that intracellular [Ca²⁺]i in C3H10T1/2 cells can be upregulated upon exposure to PEMF and that PEMF-induced C3H10T1/2 cell differentiation was Ca²⁺-dependent. The pro-osteogenic effect of PEMF on Ca²⁺-dependent osteoblast differentiation was then verified by alkaline phosphatase (ALP) and von Kossa staining. Furthermore, PEMF promoted the gene expression and protein synthesis of the Wnt/β-catenin pathway. Increased [Ca²⁺]i in the nucleoplasm was followed by the mobilization and translocation of β-catenin into the nucleus in C3H10T1/2 cells. A model of Wnt/β-catenin signaling and the Wnt/Ca2+ signaling network is proposed. Taken together, these findings indicated for the first time that PEMF induces osteoblastogenesis through increased intracellular [Ca²⁺]i and the Wnt-Ca2+/Wnt-β-catenin signaling pathway in C3H10T1/2 mesenchymal cells.

Synergistic effect of a LPEMF and SPIONs on BMMSC proliferation, directional migration, and osteoblastogenesis

Pulsed electromagnetic fields (PEMFs) represent a new type of physiotherapy that has been shown to be effective for improving bone fracture healing and treating osteoporosis. Targeted therapy with bone marrow mesenchymal stem cells (BMMSCs) has been the focus of several recent studies. The key to such therapy is the effective application of certain nanomaterials in BMMSCs so they achieve an ideal target concentration under the influence of a PEMF. In our present study, the effects of a PEMF on the process of osteoblastogenesis were systematically investigated using superparamagnetic iron oxide nanoparticle (SPION)-labeled BMMSCs. Rat BMMSCs labeled with SPIONs were exposed to a low-frequency pulsed electromagnetic field (LPEMF) of 50 Hz at 1.1 mT. Exposure to the LPEMF resulted in an enhanced proliferation of SPION-labeled BMMSCs when compared with a control group. Furthermore, observations made by transmission electron microscopy (TEM) revealed greater cell concentrations in the central zone with exposure to the LPEMF than in the peripheral zone without LPEMF stimulation, indicating that a LPEMF could induce the migration of SPION-labeled BMMSCs towards a magnetic field. Transwell experiments confirmed that combining SPIONs with a LPEMF could significantly promote the directional migration of BMMSCs. Von Kossa and ALP staining of LPEMF-exposed SPION-labeled cells was more intense, and those cells displayed higher levels of ALP activity than control cells. The SPION-labeled, LPEMF-exposed cells also showed increased levels of osteogenesis-related gene and protein expression (e.g., ALP, OCN, and RUNX2) in PCR and western blot studies. Taken together, our findings suggest that a combination of LPEMF and SPIONs exerts a synergistic effect on promoting the directional migration and osteogenic differentiation of BMMSCs, indicating that application of a LPEMF in conjunction with SPIONs may constitute a method for treating bone defects.

Pulsed Electromagnetic Fields and Tissue Engineering of the Joints

BACKGROUND

Bone and joint formation, maintenance, and regeneration are regulated by both chemical and physical signals. Among the physical signals there is an increasing realization of the role of pulsed electromagnetic fields (PEMF) in the treatment of nonunions of bone fractures. The discovery of the piezoelectric properties of bone by Fukada and Yasuda in 1953 in Japan established the foundation of this field. Pioneering research by Bassett and Brighton and their teams resulted in the approval by the Food and Drug Administration (FDA) of the use of PEMF in the treatment of fracture healing. Although PEMF has potential applications in joint regeneration in osteoarthritis (OA), this evolving field is still in its infancy and offers novel opportunities.

METHODS

We have systematically reviewed the literature on the influence of PEMF in joints, including articular cartilage, tendons, and ligaments, of publications from 2000 to 2016.

CONCLUSIONS

PEMF stimulated chondrocyte proliferation, differentiation, and extracellular matrix synthesis by release of anabolic morphogens such as bone morphogenetic proteins and anti-inflammatory cytokines by adenosine receptors A2_A and A3 in both in vitro and in vivo investigations. It is noteworthy that in clinical translational investigations a beneficial effect was observed on improving function in OA knees. However, additional systematic studies on the mechanisms of action of PEMF on joints and tissues therein, articular cartilage, tendons, and ligaments are required.

Effects of physical exercise on the cartilage of ovariectomized rats submitted to immobilization

Objective

To analyze the effects of physical exercise on cartilage histomorphometry in osteoporosis-induced rats subjected to immobilization.

Methods

We used 36 Wistar rats that were separated into six groups: G1, G2 and G3 submitted to pseudo-oophorectomy, and G4, G5 and G6 submitted to oophorectomy. After 60 days at rest, G2, G3, G5 and G6 had the right hind limbs immobilized for 15 days, followed by the same period in remobilization, being free in the box to G2 and G5, and climb ladder to G3 and G6. At the end of the experiment, the rats were euthanized, their tibias bilaterally removed and submitted to histological routine.

Results

There was significant increase in thickness of the articular cartilage (F(5;29)=13.88; p<0.0001) and epiphyseal plate (F(5;29)=14.72; p<0.0001) as the number of chondrocytes (F(5;29)=5.11; p=0.0021) in ovariectomized rats, immobilized and submitted to exercise. In the morphological analysis, degeneration of articular cartilage with subchondral bone exposure, loss of cellular organization, discontinuity of tidemark, presence of cracks and flocculation in ovariectomized, immobilized and free remobilization rats were found. In ovariectomized and immobilized remobilization ladder rats, signs of repair of the cartilaginous structures in the presence of clones, pannus, subcortical blood vessel invasion in the calcified zone, increasing the amount of isogenous groups and thickness of the calcified zone were observed.

Conclusion

Exercise climb ladder was effective in cartilaginous tissue recovery process damaged by immobilization, in model of osteoporosis by ovariectomy in rats.

Effects of ultrasound on estradiol level, bone mineral density, bone biomechanics and matrix metalloproteinase-13 expression in ovariectomized rabbits

The aim of the present study was to observe the effect of ultrasound (US) on estradiol level, bone mineral density (BMD), bone biomechanics and matrix metalloproteinase-13 (MMP-13) expression in ovariectomized (OVX) rabbits. A total of 28 virgin New Zealand white rabbits were randomly assigned into the following groups: Control (control group), ovariectomy (OVX group), ovariectomy with ultrasound therapy (US group) and ovariectomy with estrogen replacement therapy group (ERT group). At 8 weeks after ovariectomy, the US group received ultrasound treatment while the ERT group were orally treated with conjugated estrogens, and the control and OVX groups remained untreated. The estradiol level, BMD and bone biomechanics, cartilage histology and the MMP-13 expression were analyzed after the intervention. The results indicate that the US treatment increased estradiol level, BMD and bone biomechanical function. Furthermore, the US treatment appeared to improve the recovery of cartilage morphology and decreased the expression of MMP-13 in OVX models. Furthermore, the results suggest that 10 days of US therapy was sufficient to prevent the reduction of estradiol, BMD and bone biomechanical function, to protect osteoarthritis cartilage structure, and to reduce MMP-13 transcription and expression in OVX rabbits. Therefore, US treatment may be a potential treatment for postmenopausal osteoarthritis and osteoporosis.

Pulsed electromagnetic fields for postmenopausal osteoporosis and concomitant lumbar osteoarthritis in southwest China using proximal femur bone mineral density as the primary endpoint: study protocol for a randomized controlled trial

BACKGROUND

Osteoporosis (OP) and osteoarthritis (OA) are prevalent skeletal disorders among postmenopausal women. Coexistence is common especially that of postmenopausal osteoporosis (PMO) and lumbar OA. An hypothesis has been raised that OP and OA might share the same pathogenic mechanism, and pulsed electromagnetic fields (PEMFs) were reported to have anti-osteoporosis and anti-osteoarthritis properties, but this suggestion was based primarily on biomarker data. Therefore, whether these two effects could take place simultaneously has not yet been investigated. This randomized controlled trial (RCT) is designed to explore the effect of PEMFs for PMO and concomitant lumbar OA.

METHODS/DESIGN

The study will include PMO patients (postmenopausal women; aged between 50 and 70 years; have been postmenopausal for at least 5 years and diagnosed with OP using proximal femur T-score) with concomitant lumbar OA (patients with confounding disorders like diabetes, hypertension, hyperlipidemia, and previous fracture history, etcetera, will be excluded) will be randomly assigned to two arms: PEMFs group and sham PEMFs group. There will be 25 participants in each arm (50 in total) and the outcome assessment, including the primary endpoint (proximal femur bone mineral density), will be performed at 5 weeks, 3 months and 6 months after enrollment.

DISCUSSION

PMO and lumbar OA are prominent public health problem, especially for postmenopausal women. We hope this RCT will provide scientific evidence to primary care of the postmenopausal women regarding the use of these nonpharmaceutical, noninvasive modalities, PEMFs, in managing PMO and lumbar OA.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR-TRC-14005156 (28 August 2014).

Ageing and osteoarthritis: a circadian rhythm connection

Osteoarthritis (OA) is the most common joint disease, affecting articular cartilage of the joints, with currently no cure. Age is a major risk factor for OA, but despite significant advances made in the OA research field, how ageing contributes to OA is still not well understood. In this review, we will focus on one particular aspect of chondrocyte biology, i.e., circadian rhythms. Disruptions to circadian clocks have been linked to various diseases. Our recent work demonstrates autonomous clocks in chondrocytes which regulate key pathways implicated in OA. The cartilage rhythm dampens with age and clock gene expression changes during the initiation stage of OA development in an experimental mouse OA model. Research into the molecular links between ageing, circadian clocks and OA may identify novel therapeutic routes for the prevention and management of OA, such as chronotherapy, or direct targeting of clock components/circadian rhythm.

Estrogen reduces mechanical injury-related cell death and proteoglycan degradation in mature articular cartilage independent of the presence of the superficial zone tissue

OBJECTIVE

To study the effect of 17β-estradiol (E2) and the superficial zone (SFZ) on cell death and proteoglycan degradation in articular cartilage after a single injurious compression in vitro.

METHOD

Cartilage explants from the femoropatellar groove of 2 year old cows with or without the SFZ were cultured serum-free with physiological concentrations of E2 and injured by an unconfined single load compression (strain 50%, velocity 2 mm/s). After 96 h cell death was measured histomorphometrically (nuclear blebbing (NB) and TUNEL staining) and release of glycosaminoglycans (GAG) by DMMB assay.

RESULTS

Injurious compression increased significantly the number of cells with NB and TUNEL staining and release of GAG. Physiological concentrations of E2 prevented the injury-related cell death and reduced the GAG release significantly in a receptor-mediated manner (shown by co-stimulation with the antiestrogen fulvestrant/faslodex/ICI-182,780). The presence of the SFZ did not alter the NB response to either the mechanical injury or E2, but reduced the overall release of GAG significantly.

CONCLUSION

E2 prevents injury-related cell death and GAG release, and might be useful for the development of treatment options for either cartilage-related sports injuries or osteoarthritis (OA). The SFZ does not seem to play an important role in (1) the E2-related tissue response and (2) the mechanically-induced cell death in deeper regions of the explants and GAG release. The latter might be related to the unconfined nature of the injury model.