Chondroprotective effects of pulsed electromagnetic fields on human cartilage explants

Pulsed electromagnetic fields potentiate bone marrow mesenchymal stem cell chondrogenesis by regulating the Wnt/β-catenin signaling pathway

BACKGROUND

Pulsed electromagnetic fields (PEMFs) show promise as a treatment for knee osteoarthritis (KOA) by reducing inflammation and promoting chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs).

PURPOSE

To identify the efficacy window of PEMFs to induce BMSCs chondrogenic differentiation and explore the cellular mechanism under chondrogenesis of BMSCs in regular and inflammatory microenvironments.

METHODS

BMSCs were exposed to PEMFs (75 Hz, 1.6/2/3/3.8 mT) for 7 and 14 days. The histology, proliferation, migration and chondrogenesis of BMSCs were assessed to identify the optimal parameters. Using these optimal parameters, transcriptome analysis was performed to identify target genes and signaling pathways, validated through immunohistochemical assays, western blotting, and qRT-PCR, with or without the presence of IL-1β. The therapeutic effects of PEMFs and the effective cellular signaling pathways were evaluated in vivo.

RESULTS

BMSCs treated with 3 mT PEMFs showed the optimal chondrogenesis on day 7, indicated by increased expression of ACAN, COL2A, and SOX9, and decreased levels of MMP3 and MMP13 at both transcriptional and protein levels. The advantages of 3 mT PEMFs diminished in the 14-day culture groups. Transcriptome analysis identified sFRP3 as a key molecule targeted by PEMF treatment, which competitively inhibited Wnt/β-catenin signaling, regardless of IL-1β presence or duration of exposure. This inhibition of the Wnt/β-catenin pathway was also confirmed in a KOA mouse model following PEMF exposure.

CONCLUSIONS

PEMFs at 75 Hz and 3 mT are optimal in inducing early-stage chondrogenic differentiation of BMSCs. The induction and chondroprotective effects of PEMFs are mediated by sFRP3 and Wnt/β-catenin signaling, irrespective of inflammatory conditions.

Electromagnetic field-mediated chitosan/gelatin/nano-hydroxyapatite and bone-derived scaffolds regulate the osteoblastic and chondrogenic phenotypes of adipose-derived stem cells to construct osteochondral tissue engineering niche in vitro

It is critical to explore the effects of electromagnetic field (EMF) on the construction of functional osteochondral tissue, which has shown certain clinical significance for the treatment of osteochondral injury. At present, there are few studies on the effect of the direction of EMF on cells. This study aimed to investigate the effects of EMF coupling on different parameters to control adipose-derived stem cells (ADSCs) proliferation and specific chondrogenic and osteogenic differentiation at 2D level and 3D level. The proliferation and differentiation of EMF-induced ADSCs are jointly regulated by EMF and space structure. In this study, Cs7/Gel3/nHAP scaffolds were prepared with good degradation rate (86.75 ± 4.96 %) and absorb water (1100 %), and the pore size was 195.63 ± 54.72 μm. The bone-derived scaffold with a pore size of 267.17 ± 129.18 μm was obtained and its main component was hydroxyapatite. Cs7/Gel3/nHAP scaffolds and bone-derived scaffolds are suitable as 3D level materials. The optimal EMF intensity was 2 mT for chondrogenic differentiation and proliferation and 1 mT for osteogenic differentiation and proliferation. It is noteworthy that EMF has a negative correlation with ADSCs proliferation in the vertical direction at 2D level, while it has a positive correlation with ADSCs proliferation at 3D level. EMF mediated 3D osteochondral scaffold provide good strategy for osteochondral tissue engineering construction.

Pulsed Electromagnetic Fields Induce Skeletal Muscle Cell Repair by Sustaining the Expression of Proteins Involved in the Response to Cellular Damage and Oxidative Stress

Pulsed electromagnetic fields (PEMF) are employed as a non-invasive medicinal therapy, especially in the orthopedic field to stimulate bone regeneration. However, the effect of PEMF on skeletal muscle cells (SkMC) has been understudied. Here, we studied the potentiality of 1.5 mT PEMF to stimulate early regeneration of human SkMC. We showed that human SkMC stimulated with 1.5 mT PEMF for four hours repeated for two days can stimulate cell proliferation without inducing cell apoptosis or significant impairment of the metabolic activity. Interestingly, when we simulated physical damage of the muscle tissue by a scratch, we found that the same PEMF treatment can speed up the regenerative process, inducing a more complete cell migration to close the scratch and wound healing. Moreover, we investigated the molecular pattern induced by PEMF among 26 stress-related cell proteins. We found that the expression of 10 proteins increased after two consecutive days of PEMF stimulation for 4 h, and most of them were involved in response processes to oxidative stress. Among these proteins, we found that heat shock protein 70 (HSP70), which can promote muscle recovery, inhibits apoptosis and decreases inflammation in skeletal muscle, together with thioredoxin, paraoxonase, and superoxide dismutase (SOD2), which can also promote skeletal muscle regeneration following injury. Altogether, these data support the possibility of using PEMF to increase SkMC regeneration and, for the first time, suggest a possible molecular mechanism, which consists of sustaining the expression of antioxidant enzymes to control the important inflammatory and oxidative process occurring following muscle damage.

Targeting Adenosine Signalling in Knee Chondropathy: The Combined Action of Polydeoxyribonucleotide and Pulsed Electromagnetic Fields: A Current Concept Review

Chondropathy of the knee is one of the most frequent degenerative cartilage pathologies with advancing age. Scientific research has, in recent years, advanced new therapies that target adenosine A2 receptors, which play a significant role in human health against many disease states by activating different protective effects against cell sufferance and damage. Among these, it has been observed that intra-articular injections of polydeoxyribonucleotides (PDRN) and Pulsed Electromagnetic Fields (PEMF) can stimulate the adenosine signal, with significant regenerative and healing effects. This review aims to depict the role and therapeutic modulation of A2A receptors in knee chondropathy. Sixty articles aimed at providing data for our study were included in this review. The present paper highlights how intra-articular injections of PDRN create beneficial effects by reducing pain and improving functional clinical scores, thanks to their anti-inflammatory action and the important healing and regenerating power of the stimulation of cell growth, production of collagen, and the extracellular matrix. PEMF therapy is a valid option in the conservative treatment of different articular pathologies, including early OA, patellofemoral pain syndrome, spontaneous osteonecrosis of the knee (SONK), and in athletes. PEMF could also be used as a supporting therapy after an arthroscopic knee procedure total knee arthroplasty to reduce the post-operative inflammatory state. The proposal of new therapeutic approaches capable of targeting the adenosine signal, such as the intra-articular injection of PDRN and the use of PEMF, has shown excellent beneficial results compared to conventional treatments. These are presented as an extra weapon in the fight against knee chondropathy.

Combined Rehabilitation Protocol in the Treatment of Osteoarthritis of the Knee: Comparative Study of Extremely Low-Frequency Magnetic Fields and Soft Elastic Knee Brace Effect

The investigation of this observational case-control study aimed at determining the effectiveness of a combined treatment of extremely low-frequency electromagnetic fields (ELF) with a soft elastic knee brace versus ELF alone in knee osteoarthritis (KOA) with respect to a reduction in pain and functional recovery. We hypothesized that the combined use of ELF and a soft elastic knee brace may provide better results. Thirty-five patients (N = 35, divided into Group 1 = ELF and Group 2 = ELF with the soft elastic knee brace) were analyzed. The rehabilitative protocol consisted of 10 sessions of antiphlogistic and antiedema programs (first cycle) for 2 weeks, followed by twelve sessions of bone repair and connective tissue repair programs (second cycle) in patients with knee osteoarthritis (KOA) for 4 weeks. Patient evaluations were conducted at baseline (T0) and after 2 (T1) and 4 (T2) weeks of treatment. A follow-up evaluation was conducted 6 weeks after treatment (T3). The LIMFA© Therapy System was used to create multifrequency magnetoelectric fields with an intensity of 100 µT and a low-frequency field. The Incrediwear Cred 40 knee sleeve (Incred) was used for alleviating knee pain. The Visual Analogue Scale (VAS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Lysholm score (Ls) were used as outcome measures. The results showed that pain at rest (Vr), pain in motion (Vm), KOOS, and Ls were significantly affected by ELF over time. In conclusion, Group 2 had a better response in terms of pain resolution at rest (p < 0.05) and a concurrent better response at T3 in terms of functional recovery (p < 0.05).

Pain and Functional Scores in Patients Affected by Knee OA after Treatment with Pulsed Electromagnetic and Magnetic Fields: A Meta-Analysis

OBJECTIVE

The purpose of this systematic review and meta-analysis was to evaluate the effect of electromagnetic field treatment on the symptoms of knee osteoarthritis (OA). In addition, the influence of the type of control group and other covariates have been investigated to identify the sources of heterogeneity in the results of the available clinical trials.

METHODS

Randomized controlled trials reporting pulsed electromagnetic field-based therapies for the treatment of knee OA have been included. Main outcomes were self-reported pain and activity scores collected by Visual Analogue Scale (VAS) and/or Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) at short term after treatment.

RESULTS

Thirteen studies comprising 914 unique patients were included in the analysis. Overall reduction in pain score was observed after treatment (standardized mean difference -0.4059, P = 0.0091), while improvement in the activity score was not significant (standardized mean difference -0.4452, P = 0.0859). Type of control (i.e., placebo or alternative therapies) and time of follow-up resulted as the two major elements influencing the outcomes. Indeed, the restriction of the analysis to placebo-controlled trials demonstrated higher standardized mean differences between treatment and control groups, with lower P value for pain, while statistical significance became evident also for the activity score. On the contrary, no differences were observed pooling only studies comparing pulsed electromagnetic or magnetic fields to alternative treatments. In addition, longer follow-up correlated with lower differences between treated and control patients.

CONCLUSIONS

Pulsed electromagnetic field therapy effectively relieves knee OA symptoms at short term, but it is not superior to other conservative therapies such as physiotherapy.

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.

Biophysical Stimulation in Athletes' Joint Degeneration: A Narrative Review

Osteoarthritis (OA) is the most prevalent degenerative joint disease and the main cause of pain and disability in elderly people. OA currently represents a significant social health problem, since it affects 250 million individuals worldwide, mainly adults aged over 65. Although OA is a multifactorial disease, depending on both genetic and environmental factors, it is reported that joint degeneration has a higher prevalence in former athletes. Repetitive impact and loading, joint overuse and recurrent injuries followed by a rapid return to the sport might explain athletes' predisposition to joint articular degeneration. In recent years, however, big efforts have been made to improve the prevention and management of sports injuries and to speed up the athletes' return-to-sport. Biophysics is the study of biological processes and systems using physics-based methods or based on physical principles. Clinical biophysics has recently evolved as a medical branch that investigates the relationship between the human body and non-ionizing physical energy. A physical stimulus triggers a biological response by regulating specific intracellular pathways, thus acting as a drug. Preclinical and clinical trials have shown positive effects of biophysical stimulation on articular cartilage, subchondral bone and synovia. This review aims to assess the role of pulsed electromagnetic fields (PEMFs) and extracorporeal shockwave therapy (ESWT) in the prevention and treatment of joint degeneration in athletes.

Tissue Engineering Strategies to Increase Osteochondral Regeneration of Stem Cells; a Close Look at Different Modalities

The homeostasis of osteochondral tissue is tightly controlled by articular cartilage chondrocytes and underlying subchondral bone osteoblasts via different internal and external clues. As a correlate, the osteochondral region is frequently exposed to physical forces and mechanical pressure. On this basis, distinct sets of substrates and physicochemical properties of the surrounding matrix affect the regeneration capacity of chondrocytes and osteoblasts. Stem cells are touted as an alternative cell source for the alleviation of osteochondral diseases. These cells appropriately respond to the physicochemical properties of different biomaterials. This review aimed to address some of the essential factors which participate in the chondrogenic and osteogenic capacity of stem cells. Elements consisted of biomechanical forces, electrical fields, and biochemical and physical properties of the extracellular matrix are the major determinant of stem cell differentiation capacity. It is suggested that an additional certain mechanism related to signal-transduction pathways could also mediate the chondro-osteogenic differentiation of stem cells. The discovery of these clues can enable us to modulate the regeneration capacity of stem cells in osteochondral injuries and lead to the improvement of more operative approaches using tissue engineering modalities.

[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.

Establishment of a New Device for Electrical Stimulation of Non-Degenerative Cartilage Cells In Vitro

In cell-based therapies for cartilage lesions, the main problem is still the formation of fibrous cartilage, caused by underlying de-differentiation processes ex vivo. Biophysical stimulation is a promising approach to optimize cell-based procedures and to adapt them more closely to physiological conditions. The occurrence of mechano-electrical transduction phenomena within cartilage tissue is physiological and based on streaming and diffusion potentials. The application of exogenous electric fields can be used to mimic endogenous fields and, thus, support the differentiation of chondrocytes in vitro. For this purpose, we have developed a new device for electrical stimulation of chondrocytes, which operates on the basis of capacitive coupling of alternating electric fields. The reusable and sterilizable stimulation device allows the simultaneous use of 12 cavities with independently applicable fields using only one main supply. The first parameter settings for the stimulation of human non-degenerative chondrocytes, seeded on collagen type I elastin-based scaffolds, were derived from numerical electric field simulations. Our first results suggest that applied alternating electric fields induce chondrogenic re-differentiation at the gene and especially at the protein level of human de-differentiated chondrocytes in a frequency-dependent manner. In future studies, further parameter optimizations will be performed to improve the differentiation capacity of human cartilage cells.

Pulsed Electromagnetic Field Inhibits Synovitis via Enhancing the Efferocytosis of Macrophages

Synovitis plays an important role in the pathogenesis of arthritis, which is closely related to the joint swell and pain of patients. The purpose of this study was to investigate the anti-inflammatory effects of pulsed electromagnetic fields (PEMF) on synovitis and its underlying mechanisms. Destabilization of the medial meniscus (DMM) model and air pouch inflammation model were established to induce synovitis in C57BL/6 mice. The mice were then treated by PEMF (pulse waveform, 1.5 mT, 75 Hz, 10% duty cycle). The synovitis scores as well as the levels of IL-1β and TNF-α suggested that PEMF reduced the severity of synovitis in vivo. Moreover, the proportion of neutrophils in the synovial-like layer was decreased, while the proportion of macrophages increased after PEMF treatment. In addition, the phagocytosis of apoptotic neutrophils by macrophages (efferocytosis) was enhanced by PEMF. Furthermore, the data from western blot assay showed that the phosphorylation of P38 was inhibited by PEMF. In conclusion, our current data show that PEMF noninvasively exhibits the anti-inflammatory effect on synovitis via upregulation of the efferocytosis in macrophages, which may be involved in the phosphorylation of P38.

Pulsed electromagnetic fields promote repair of focal articular cartilage defects with engineered osteochondral constructs

Articular cartilage injuries are a common source of joint pain and dysfunction. We hypothesized that pulsed electromagnetic fields (PEMFs) would improve growth and healing of tissue-engineered cartilage grafts in a direction-dependent manner. PEMF stimulation of engineered cartilage constructs was first evaluated in vitro using passaged adult canine chondrocytes embedded in an agarose hydrogel scaffold. PEMF coils oriented parallel to the articular surface induced superior repair stiffness compared to both perpendicular PEMF (p = .026) and control (p = .012). This was correlated with increased glycosaminoglycan deposition in both parallel and perpendicular PEMF orientations compared to control (p = .010 and .028, respectively). Following in vitro optimization, the potential clinical translation of PEMF was evaluated in a preliminary in vivo preclinical adult canine model. Engineered osteochondral constructs (∅ 6 mm × 6 mm thick, devitalized bone base) were cultured to maturity and implanted into focal defects created in the stifle (knee) joint. To assess expedited early repair, animals were assessed after a 3-month recovery period, with microfracture repairs serving as an additional clinical control. In vivo, PEMF led to a greater likelihood of normal chondrocyte (odds ratio [OR]: 2.5, p = .051) and proteoglycan (OR: 5.0, p = .013) histological scores in engineered constructs. Interestingly, engineered constructs outperformed microfracture in clinical scoring, regardless of PEMF treatment (p < .05). Overall, the studies provided evidence that PEMF stimulation enhanced engineered cartilage growth and repair, demonstrating a potential low-cost, low-risk, noninvasive treatment modality for expediting early cartilage repair.

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.

Efficacy of pulsed electromagnetic fields and electromagnetic fields tuned to the ion cyclotron resonance frequency of Ca2+ on chondrogenic differentiation

Previous studies provide strong evidence for the therapeutic effect of electromagnetic fields (EMFs) on different tissues including cartilage. Diverse exposure parameters applied in scientific reports and the unknown interacting mechanism of EMF with biological systems make EMF studies challenging. In 1985, Liboff proposed that when magnetic fields are tuned to the cyclotron resonance frequencies of critical ions, the motion of ions through cell membranes is enhanced, and thus biological effects appear. Such exposure system consists of a weak alternating magnetic field (B₁ ) in the presence of a static magnetic field (B₀ ) and depends on the relationship between the magnitudes of B₀ and B₁ and the angular frequency Ω. The purpose of the present study is to determine the chondrogenic potential of EMF with regards to pulsed EMF (PEMF) and the ion cyclotron resonance (ICR) theory. We used different stimulating systems to generate EMFs in which cells are either stimulated with ubiquitous PEMF parameters, frequently reported, or parameters tuned to satisfy the ICR for Ca²⁺ (including negative and positive control groups). Chondrogenesis was analysed after 3 weeks of treatment. Cell stimulation under the ICR condition showed positive results in the context of glycosaminoglycans and type II collagen synthesis. In contrast, the other electromagnetically stimulated groups showed no changes compared with the control groups. Furthermore, gene expression assays revealed an increase in the expression of chondrogenic markers (COL2A1, SOX9, and ACAN) in the ICR group. These results suggest that the Ca²⁺ ICR condition can be an effective factor in inducing chondrogenesis.

Biophysical Stimuli: A Review of Electrical and Mechanical Stimulation in Hyaline Cartilage

OBJECTIVE

Hyaline cartilage degenerative pathologies induce morphologic and biomechanical changes resulting in cartilage tissue damage. In pursuit of therapeutic options, electrical and mechanical stimulation have been proposed for improving tissue engineering approaches for cartilage repair. The purpose of this review was to highlight the effect of electrical stimulation and mechanical stimuli in chondrocyte behavior.

DESIGN

Different information sources and the MEDLINE database were systematically revised to summarize the different contributions for the past 40 years.

RESULTS

It has been shown that electric stimulation may increase cell proliferation and stimulate the synthesis of molecules associated with the extracellular matrix of the articular cartilage, such as collagen type II, aggrecan and glycosaminoglycans, while mechanical loads trigger anabolic and catabolic responses in chondrocytes.

CONCLUSION

The biophysical stimuli can increase cell proliferation and stimulate molecules associated with hyaline cartilage extracellular matrix maintenance.

Clinical results of pulsed signal therapy on patellofemoral syndrome with patellar chondropathy

This study was designed to evaluate the effect of pulsed signal therapy (PST) on patellofemoral pain syndrome associated with patellar chondropathy. A prospective randomized double-blind placebo controlled trial included 25 patients (41 knees) between 20 and 50 years with pain due to isolated patellofemoral syndrome with chondropathy. PST group received nine 60-min daily sessions of PST treatment. Control group received the same protocol of blinded placebo treatment. The main outcome was change from baseline Kujala score at 3 months. After 3 months, patients in the control group received effective treatment (placebo post-treatment). All patients were then followed, for up to 12 months. Seventeen knees (5 males and 12 females, mean age 36.7 ± 7.9) received placebo and 24 knees (8 males and 16 females, mean age 35.5 ± 8.9) received PST. By the third month, PST group exhibited a mean change from baseline of 9.63 ± 7.5 Kujala points, compared to 0.53 ± 1.8 in the placebo group (P < 0.001). A significant progressive improvement was seen in the PST group between the 3rd and 6th and between the 6th and 12th month (P < 0.016). Patients initially allocated in the control group also improved at 3 months (P < 0.001) and 6 months (P = 0.005) post-effective treatment. In conclusion, PST in patellofemoral pain syndrome with chondropathy was effective compared to placebo at 3 months, showing an important improvement of Kujala score. The improvement was progressive and maintained up to 12 months. PST is safe and should be considered as a non-invasive option for management of this condition. Bioelectromagnetics. 40:83-90, 2019. © 2019 Bioelectromagnetics Society.

Biophysical stimulation of bone and cartilage: state of the art and future perspectives

INTRODUCTION

Biophysical stimulation is a non-invasive therapy used in orthopaedic practice to increase and enhance reparative and anabolic activities of tissue.

METHODS

A sistematic web-based search for papers was conducted using the following titles: (1) pulsed electromagnetic field (PEMF), capacitively coupled electrical field (CCEF), low intensity pulsed ultrasound system (LIPUS) and biophysical stimulation; (2) bone cells, bone tissue, fracture, non-union, prosthesis and vertebral fracture; and (3) chondrocyte, synoviocytes, joint chondroprotection, arthroscopy and knee arthroplasty.

RESULTS

Pre-clinical studies have shown that the site of interaction of biophysical stimuli is the cell membrane. Its effect on bone tissue is to increase proliferation, synthesis and release of growth factors. On articular cells, it creates a strong A_2A and A₃ adenosine-agonist effect inducing an anti-inflammatory and chondroprotective result. In treated animals, it has been shown that the mineralisation rate of newly formed bone is almost doubled, the progression of the osteoarthritic cartilage degeneration is inhibited and quality of cartilage is preserved. Biophysical stimulation has been used in the clinical setting to promote the healing of fractures and non-unions. It has been successfully used on joint pathologies for its beneficial effect on improving function in early OA and after knee surgery to limit the inflammation of periarticular tissues.

DISCUSSION

The pooled result of the studies in this review revealed the efficacy of biophysical stimulation for bone healing and joint chondroprotection based on proven methodological quality.

CONCLUSION

The orthopaedic community has played a central role in the development and understanding of the importance of the physical stimuli. Biophysical stimulation requires care and precision in use if it is to ensure the success expected of it by physicians and patients.

Physical Stimulations for Bone and Cartilage Regeneration

A wide range of techniques and methods are actively invented by clinicians and scientists who are dedicated to the field of musculoskeletal tissue regeneration. Biological, chemical, and physiological factors, which play key roles in musculoskeletal tissue development, have been extensively explored. However, physical stimulation is increasingly showing extreme importance in the processes of osteogenic and chondrogenic differentiation, proliferation and maturation through defined dose parameters including mode, frequency, magnitude, and duration of stimuli. Studies have shown manipulation of physical microenvironment is an indispensable strategy for the repair and regeneration of bone and cartilage, and biophysical cues could profoundly promote their regeneration. In this article, we review recent literature on utilization of physical stimulation, such as mechanical forces (cyclic strain, fluid shear stress, etc.), electrical and magnetic fields, ultrasound, shock waves, substrate stimuli, etc., to promote the repair and regeneration of bone and cartilage tissue. Emphasis is placed on the mechanism of cellular response and the potential clinical usage of these stimulations for bone and cartilage regeneration.

Stochastic Resonance with Dynamic Compression Improves the Growth of Adult Chondrocytes in Agarose Gel Constructs

Dynamic mechanical stimulation has been an effective method to improve the growth of tissue engineering cartilage constructs derived from immature cells. However, when more mature cell populations are used, results are often variable due to the differing responses of these cells to external stimuli. This can be especially detrimental in the case of mechanical loading. In previous studies, multi-modal mechanical stimulation in the form of stochastic resonance was shown to be effective at improving the growth of young bovine chondrocytes. Thus, the aim of this study was to investigate the short-term and long-term effects of stochastic resonance on two groups of bovine chondrocytes, adult (> 30 month) and juvenile (~ 18 months). While the juvenile cells outperformed the adult cells in terms of their anabolic response to loading, combined mechanical loading for both age groups resulted in greater matrix synthesis compared to compressive loading alone. In the adult cells, potential pathological tissue formation was evident with the presence of cell clustering. However, the presence of broad-band mechanical vibrations (alone or with compressive loading) appeared to mitigate this response and allow these cells to attain a growth response similar to the juvenile, unstimulated cells. Therefore, the use of stochastic resonance appears to show promise as a method to improve the formation and properties of tissue engineered cartilage constructs, irrespective of cell age.

Effect of electric stimulation on human chondrocytes and mesenchymal stem cells under normoxia and hypoxia

During joint movement and mechanical loading, electric potentials occur within cartilage tissue guiding cell development and regeneration. Exposure of cartilage exogenous electric stimulation (ES) may imitate these endogenous electric fields and promote healing processes. Therefore, the present study investigated the influence of electric fields on human chondrocytes, mesenchymal stem cells and the co-culture of the two. Human chondrocytes isolated from articular cartilage obtained post-mortally and human mesenchymal stem cells derived from bone marrow (BM-MSCs) were seeded onto a collagen-based scaffold separately or as co-culture. Following incubation with the growth factors over 3 days, ES was performed using titanium electrodes applying an alternating electric field (700 mV, 1 kHz). Cells were exposed to an electric field over 7 days under either hypoxic or normoxic culture conditions. Following this, metabolic activity was investigated and synthesis rates of extracellular matrix proteins were analyzed. ES did not influence metabolic activity of chondrocytes or BM-MSCs. Gene expression analyses demonstrated that ES increased the expression of collagen type II mRNA and aggrecan mRNA in human chondrocytes under hypoxic culture conditions. Likewise, collagen type II synthesis was significantly increased following exposure to electric fields under hypoxia. BM-MSCs and the co-culture of chondrocytes and BM-MSCs revealed a similar though weaker response regarding the expression of cartilage matrix proteins. The electrode setup may be a valuable tool to investigate the influence of ES on human chondrocytes and BM-MSCs contributing to fundamental knowledge including future applications of ES in cartilage repair.

Short Exposures to an Extremely Low-Frequency Magnetic Field (ELF MF) Enhance Protein but not mRNA Alkaline Phosphatase Expression in Human Osteosarcoma Cells

Background

Among electromagnetic fields treatments used in orthopedics, extremely low-frequency magnetic fields (ELF MF) need more detailed information about the molecular mechanisms of their effects and exposure conditions.

Objective

Evaluation of the effects of an ELF MF exposure system, recently introduced among current clinical treatments for fracture healing and other bone diseases, on Alkaline Phosphatase (ALP) activity and expression in a human osteosarcoma cell line (SaOS-2), as marker typically associated to osteogenesis and bone tissue regeneration.

Method

Cells were exposed to the ELF MF physical stimulus (75 Hz, 1.5 mT) for 1h. Cell viability, enzymatic activity, protein and mRNA expression of alkaline phosphatase were then measured at different times after exposure (0, 4 and 24 h).

Results

Data demonstrate that this signal is active on an osteogenic process already one hour after exposure. Treatment was, in fact, capable, even after an exposure shorter than those commonly used in clinical applications, to significantly up-regulate alkaline phosphatase enzymatic activity. This regulation is produced essentially through an increase of ALP protein level, without changes of its mRNA concentration, while assessed magnetic field did not affect cell growth and viability and did not produce temperature variations.

Conclusion

Tested low-frequency magnetic field affects cellular ALP expression with a posttranslational mechanism, without the involvement of regulations at gene transcription and mRNA level. This molecular effect is likely produced even within treated tissues during therapies with this signal and may be implicated in the induction of observed effects in treated patients.

No superior treatment for primary osteochondral defects of the talus

PURPOSE

The purpose of this systematic literature review is to detect the most effective treatment option for primary talar osteochondral defects in adults.

METHODS

A literature search was performed to identify studies published from January 1996 to February 2017 using PubMed (MEDLINE), EMBASE, CDSR, DARE, and CENTRAL. Two authors separately and independently screened the search results and conducted the quality assessment using the Newcastle-Ottawa Scale. Subsequently, success rates per separate study were calculated. Studies methodologically eligible for a simplified pooling method were combined.

RESULTS

Fifty-two studies with 1236 primary talar osteochondral defects were included of which forty-one studies were retrospective and eleven prospective. Two randomised controlled trials (RCTs) were identified. Heterogeneity concerning methodological nature was observed, and there was variety in reported success rates. A simplified pooling method performed for eleven retrospective case series including 317 ankles in the bone marrow stimulation group yielded a success rate of 82% [CI 78-86%]. For seven retrospective case series investigating an osteochondral autograft transfer system or an osteoperiosteal cylinder graft insertion with in total 78 included ankles the pooled success rate was calculated to be 77% [CI 66-85%].

CONCLUSIONS

For primary talar osteochondral defects, none of the treatment options showed any superiority over others.

LEVEL OF EVIDENCE

IV.

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.

Effect of electromagnetic fields on human osteoarthritic and non-osteoarthritic chondrocytes

BACKGROUND

Studies of the effects of electromagnetic fields (EMFs) on cartilaginous cells show a broad range of outcomes. However EMFs are not yet clinically applied as standard treatment of osteoarthritis, as EMF effects are showing varying outcomes in the literature. The aim of this study was to examine effects of EMFs (5 mT or 8 mT) on osteoarthritic (OA) and non-OA chondrocytes in order to investigate whether EMF effects are related to chondrocyte and EMF quality.

METHODS

Pellets of human OA and non-OA chondrocytes were exposed to a sinusoidal 15 Hz EMF produced by a solenoid. Control groups were cultivated without EMF under standard conditions for 7 days. Cultures were examined by staining, immunohistochemistry and quantitative real-time PCR for RNA corresponding to cartilage specific proteins (COL2A1, ACAN, SOX9).

RESULTS

OA chondrocytes increased the expression of COL2A1 and ACAN under 5 mT EMF compared to control. In contrast no changes in gene expression were observed in non-OA chondrocytes. OA and non-OA chondrocytes showed no significant changes in gene expression under 8 mT EMF.

CONCLUSION

A 5 mT EMF increased the expression of cartilage specific genes in OA chondrocytes whereas in non-OA chondrocytes no changes in gene expression were observed. An 8 mT EMF however showed no effect altogether. This suggests that EMF effects are related to EMF but also to chondrocyte quality. Further studies about the clinical relevance of this effect are necessary.

Notch pathway is active during osteogenic differentiation of human bone marrow mesenchymal stem cells induced by pulsed electromagnetic fields

Pulsed electromagnetic fields (PEMFs) have been used to treat bone diseases, particularly nonunion healing. Although it is known that PEMFs promote the osteogenic differentiation of human mesenchymal stem cells (hMSCs), to date PEMF molecular mechanisms remain not clearly elucidated. The Notch signalling is a highly conserved pathway that regulates cell fate decisions and skeletal development. The aim of this study was to investigate if the known PEMF-induced osteogenic effects may involve the modulation of the Notch pathway. To this purpose, during in vitro osteogenic differentiation of bone marrow hMSCs in the absence and in the presence of PEMFs, osteogenic markers (alkaline phosphatase activity, osteocalcin and matrix mineralization), the messenger ribonucleic acid expression of osteogenic transcription factors (Runx2, Dlx5, Osterix) as well as of Notch receptors (Notch1-4), their ligands (Jagged1, Dll1 and Dll4) and nuclear target genes (Hes1, Hes5, Hey1, Hey2) were investigated. PEMFs stimulated all osteogenic markers and increased the expression of Notch4, Dll4, Hey1, Hes1 and Hes5 in osteogenic medium compared to control. In the presence of DAPT and SAHM1, used as Notch pathway inhibitors, the expression of the osteogenic markers, including Runx2, Dlx5, Osterix, as well as Hes1 and Hes5 were significantly inhibited, both in unexposed and PEMF-exposed hMSCs. These results suggest that activation of Notch pathway is required for PEMFs-stimulated osteogenic differentiation. These new findings may be useful to improve autologous cell-based regeneration of bone defects in orthopaedics.

Polydeoxyribonucleotides (PDRNs) From Skin to Musculoskeletal Tissue Regeneration via Adenosine A2A Receptor Involvement

Polydeoxyribonucleotides (PDRNs) are low molecular weight DNA molecules of natural origin that stimulate cell migration and growth, extracellular matrix (ECM) protein production, and reduce inflammation. Most preclinical and clinical studies on tissue regeneration with PDRNs focused on skin, and only few are about musculoskeletal tissues. Starting from an overview on skin regeneration studies, through the analysis of in vitro, in vivo, and clinical studies (1990-2016), the present review aimed at defining the effects of PDRN and their mechanisms of action in the regeneration of musculoskeletal tissues. This would also help future researches in this area. A total of 29 studies were found by PubMed and www.webofknowledge.com searches: 20 were on skin (six in vitro, six in vivo, one vitro/vivo, seven clinical studies), while the other nine regarded bone (one in vitro, two in vivo, one clinical studies), cartilage (one in vitro, one vitro/vivo, two clinical studies), or tendon (one clinical study) tissues regeneration. PDRNs improved cell growth, tissue repair, ECM proteins, physical activity, and reduced pain and inflammation, through the activation of adenosine A_2A receptor. PDRNs are currently used for bone, cartilage, and tendon diseases, with a great variability regarding the PDRN dosage to be used in clinical practice, while the dosage for skin regeneration is well established. PDRNs are usually administered from a minimum of three to a maximum of five times and they act trough the activation of A_2A receptor. Further studies are advisable to confirm the effectiveness of PDRNs and to standardize the PDRN dose. J. Cell. Physiol. 232: 2299-2307, 2017. © 2016 Wiley Periodicals, Inc.

Adenosine Receptors as a Biological Pathway for the Anti-Inflammatory and Beneficial Effects of Low Frequency Low Energy Pulsed Electromagnetic Fields

Several studies explored the biological effects of low frequency low energy pulsed electromagnetic fields (PEMFs) on human body reporting different functional changes. Much research activity has focused on the mechanisms of interaction between PEMFs and membrane receptors such as the involvement of adenosine receptors (ARs). In particular, PEMF exposure mediates a significant upregulation of A_2A and A₃ARs expressed in various cells or tissues involving a reduction in most of the proinflammatory cytokines. Of particular interest is the observation that PEMFs, acting as modulators of adenosine, are able to increase the functionality of the endogenous agonist. By reviewing the scientific literature on joint cells, a double role for PEMFs could be hypothesized in vitro by stimulating cell proliferation, colonization of the scaffold, and production of tissue matrix. Another effect could be obtained in vivo after surgical implantation of the construct by favoring the anabolic activities of the implanted cells and surrounding tissues and protecting the construct from the catabolic effects of the inflammatory status. Moreover, a protective involvement of PEMFs on hypoxia damage in neuron-like cells and an anti-inflammatory effect in microglial cells have suggested the hypothesis of a positive impact of this noninvasive biophysical stimulus.

Pulsed Electromagnetic Field Exposure Reduces Hypoxia and Inflammation Damage in Neuron-Like and Microglial Cells

In the present study, the effect of low-frequency, low-energy pulsed electromagnetic fields (PEMFs) has been investigated by using different cell lines derived from neuron-like cells and microglial cells. In particular, the primary aim was to evaluate the effect of PEMF exposure in inflammation- and hypoxia-induced injury in two different neuronal cell models, the human neuroblastoma-derived SH-SY5Y cells and rat pheochromocytoma PC12 cells and in N9 microglial cells. In neuron-like cells, live/dead and apoptosis assays were performed in hypoxia conditions from 2 to 48 h. Interestingly, PEMF exposure counteracted hypoxia damage significantly reducing cell death and apoptosis. In the same cell lines, PEMFs inhibited the activation of the hypoxia-inducible factor 1α (HIF-1α), the master transcriptional regulator of cellular response to hypoxia. The effect of PEMF exposure on reactive oxygen species (ROS) production in both neuron-like and microglial cells was investigated considering their key role in ischemic injury. PEMFs significantly decreased hypoxia-induced ROS generation in PC12, SH-SY5Y, and N9 cells after 24 or 48 h of incubation. Moreover, PEMFs were able to reduce some of the most well-known pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and IL-8 release in N9 microglial cells stimulated with different concentrations of LPS for 24 or 48 h of incubation time. These results show a protective effect of PEMFs on hypoxia damage in neuron-like cells and an anti-inflammatory effect in microglial cells suggesting that PEMFs could represent a potential therapeutic approach in cerebral ischemic conditions. J. Cell. Physiol. 232: 1200-1208, 2017. © 2016 Wiley Periodicals, Inc.

Pulsed electromagnetic field (PEMF) treatment reduces expression of genes associated with disc degeneration in human intervertebral disc cells

BACKGROUND CONTEXT

Pulsed electromagnetic field (PEMF) therapies have been applied to stimulate bone healing and to reduce the symptoms of arthritis, but the effects of PEMF on intervertebral disc (IVD) biology is unknown.

PURPOSE

The purpose of this study was to determine how PEMF affects gene expression of IVD cells in normal and inflammatory environments.

STUDY DESIGN/SETTING

This was an in vitro human cell culture and microarray gene expression study.

METHODS

Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were separately encapsulated in alginate beads and exposed to interleukin 1α (IL-1α) (10 ng/mL) to stimulate the inflammatory environment associated with IVD degeneration and/or stimulated by PEMF for 4 hours daily for up to 7 days. RNA was isolated from each treatment group and analyzed via microarray to assess IL-1α- and PEMF-induced changes in gene expression.

RESULTS

Although PEMF treatment did not completely inhibit the effects of IL-1α, PEMF treatment lessened the IL-1α-induced upregulation of genes expressed in degenerated IVDs. Consistent with our previous results, after 4 days, PEMF tended to reduce IL-1α-associated gene expression of IL-6 (25%, p=.07) in NP cells and MMP13 (26%, p=.10) in AF cells. Additionally, PEMF treatment significantly diminished IL-1α-induced gene expression of IL-17A (33%, p=.01) and MMP2 (24%, p=.006) in NP cells and NFκB (11%, p=.04) in AF cells.

CONCLUSIONS

These results demonstrate that IVD cells are responsive to PEMF and motivate future studies to determine whether PEMF may be helpful for patients with IVD degeneration.

Effects of Pulsed Electromagnetic Fields on Return to Sports After Arthroscopic Debridement and Microfracture of Osteochondral Talar Defects: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial

BACKGROUND

Osteochondral defects (OCDs) of the talus usually affect athletic patients. The primary surgical treatment consists of arthroscopic debridement and microfracture. Various possibilities have been suggested to improve the recovery process after debridement and microfracture. A potential solution to obtain this goal is the application of pulsed electromagnetic fields (PEMFs), which stimulate the repair process of bone and cartilage.

HYPOTHESIS

The use of PEMFs after arthroscopic debridement and microfracture of an OCD of the talus leads to earlier resumption of sports and an increased number of patients that resume sports.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 68 patients were randomized to receive either PEMFs (n = 36) or placebo (n = 32) after arthroscopic treatment of an OCD of the talus. The primary outcomes (ie, the number of patients who resumed sports and time to resumption of sports) were analyzed with Kaplan-Meier curves as well as Mann-Whitney U, chi-square, and log-rank tests. Secondary functional outcomes were assessed with questionnaires (American Orthopaedic Foot and Ankle Society ankle-hindfoot score, Foot and Ankle Outcome Score, EuroQol, and numeric rating scales for pain and satisfaction) at multiple time points up to 1-year follow-up. To assess bone repair, computed tomography scans were obtained at 2 weeks and 1 year postoperatively.

RESULTS

Almost all outcome measures improved significantly in both groups. The percentage of sport resumption (PEMF, 79%; placebo, 80%; P = .95) and median time to sport resumption (PEMF, 17 weeks; placebo, 16 weeks; P = .69) did not differ significantly between the treatment groups. Likewise, there were no significant between-group differences with regard to the secondary functional outcomes and the computed tomography results.

CONCLUSION

PEMF does not lead to a higher percentage of patients who resume sports or to earlier resumption of sports after arthroscopic debridement and microfracture of talar OCDs. Furthermore, no differences were found in bone repair between groups.

REGISTRATION

Netherlands Trial Register NTR1636.

Effects of electromagnetic field frequencies on chondrocytes in 3D cell-printed composite constructs

In cartilage tissue engineering, electromagnetic field (EMF) therapy has been reported to have a modest effect on promoting cartilage regeneration. However, these studies were conducted using different frequencies of EMF to stimulate chondrocytes. Thus, it is necessary to investigate the effect of EMF frequency on cartilage formation. In addition to the stimulation, a scaffold is required to satisfy the characteristics of cartilage such as its hydrated and dense extracellular matrix, and a mechanical resilience to applied loads. Therefore, we 3D-printed a composite construct composed of a polymeric framework and a chondrocyte-laden hydrogel. Here, we observed frequency-dependent positive and negative effects on chondrogenesis using a 3D cell-printed cartilage tissue. We found that a frequency of 45 Hz promoted gene expression and secretion of extracellular matrix molecules of chondrocytes. In contrast, a frequency of 7.5 Hz suppressed chondrogenic differentiation in vitro. Additionally, the EMF-treated composite constructs prior to implantation showed consistent results with those of in vitro, suggesting that in vitro pre-treatment with different EMF frequencies provides different capabilities for the enhancement of cartilage formation in vivo. This correlation between EMF frequency and 3D-printed chondrocytes suggests the necessity for optimization of EMF parameters when this physical stimulus is applied to engineered cartilage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1797-1804, 2016.

Pulsed electromagnetic fields promote survival and neuronal differentiation of human BM-MSCs

Pulsed electromagnetic fields (PEMF) are known to affect biological properties such as differentiation, regulation of transcription factor and cell proliferation. However, the cell-protective effect of PEMF exposure is largely unknown. The aim of this study is to understand the mechanisms underlying PEMF-mediated suppression of apoptosis and promotion of survival, including PEMF-induced neuronal differentiation. Treatment of induced human BM-MSCs with PEMF increased the expression of neural markers such as NF-L, NeuroD1 and Tau. Moreover, treatment of induced human BM-MSCs with PEMF greatly decreased cell death in a dose- and time-dependent manner. There is evidence that Akt and Ras are involved in neuronal survival and protection. Activation of Akt and Ras results in the regulation of survival proteins such as Bad and Bcl-xL. Thus, the Akt/Ras signaling pathway may be a desirable target for enhancing cell survival and treatment of neurological disease. Our analyses indicated that PEMF exposure dramatically increased the activity of Akt, Rsk, Creb, Erk, Bcl-xL and Bad via phosphorylation. PEMF-dependent cell protection was reversed by pretreatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K). Our data suggest that the PI3K/Akt/Bad signaling pathway may be a possible mechanism for the cell-protective effects of PEMF.

Experimentally induced cartilage degeneration treated by pulsed electromagnetic field stimulation; an in vitro study on bovine cartilage

BACKGROUND

Osteoarthritis (OA) is the final result of progressive alterations to articular cartilage structure, composition and cellularity, followed by an increase in the concentration of pro-inflammatory cytokines in joint synovial fluid. Even though the effect of pulsed electromagnetic field (PEMF) stimulation in counteracting OA progression and inflammation is of increasing interest, because of its anabolic and anti-inflammatory properties, the present study aimed to improve the knowledge on cartilage extracellular matrix (ECM) and chondrocyte changes related to the exposure of PEMF, from a histological and histomorphometric point of view.

METHODS

An in vitro OA model was realized, culturing bovine cartilage explants with a high dose of interleukin 1β (IL1β, 50 ng/ml) at different experimental times (24 h, and 7 and 21 days). The effects of PEMFs (75 Hz, 1.5 mT) were evaluated in cartilage explants treated with IL1β or not (control), in terms of cartilage structure, cellularity and proteoglycans, glycosaminoglycans, collagen II and transforming growth factor β1 synthesis by using histology, histomorphometry and immunohistochemistry.

RESULTS

Making a comparison with control cartilage, IL1β-treated explants showed a decrease in cartilage matrix, structure and cellularity parameters. PEMFs were able to counteract the progression of OA acting on both cartilage cellularity and ECM in cartilage previously treated with IL1β. Normal distribution (Kolmogroc-Smirnov test) and homoscedasticity (Levene test) of data were verified, then, the non-parametric Kruskal Wallis test followed by Mann-Whiteny U test for pairwise comparisons were performed. The p-value was adjusted according to the Dunn-Sidak correction.

CONCLUSIONS

These results, obtained by culturing and treating cartilage explants from two different joints, confirmed that PEMF stimulation can be used as adjuvant therapy to preserve cartilage from detrimental effects of high inflammatory cytokine levels during OA.

BEMER Therapy Combined with Physiotherapy in Patients with Musculoskeletal Diseases: A Randomised, Controlled Double Blind Follow-Up Pilot Study

Background. This study evaluates the effect of adjuvant BEMER therapy in patients with knee arthrosis and chronic low back pain in a randomized double blind design. Methods. A total of 50 patients with chronic low back pain and 50 patients with osteoarthritis of knee took part in this study and were randomized into 4 groups. Hospitalized patients received a standardized physiotherapy package for 3 weeks followed by BEMER therapy or placebo. Results. In patients with low back pain, the comparison of the results obtained at the first and second visit showed a significant improvement in resting VAS scores and Fatigue Scale scores. The Oswestry scores and Quality of Life Scale scores showed no change. In patients with knee arthrosis, the comparison of the first and second measurements showed no significant improvement in the abovementioned parameters, while the comparison of the first and third scores revealed a significant improvement in the Fatigue Scale scores and in the vitality test on the Quality of Life Scale. Conclusions. Our study showed that BEMER physical vascular therapy reduced pain and fatigue in the short term in patients with chronic low back pain, while long-term therapy appears to be beneficial in patients with osteoarthritis of knee.

Physicochemical and biomechanical stimuli in cell-based articular cartilage repair

Articular cartilage is a unique load-bearing connective tissue with a low intrinsic capacity for repair and regeneration. Its avascularity makes it relatively hypoxic and its unique extracellular matrix is enriched with cations, which increases the interstitial fluid osmolarity. Several physicochemical and biomechanical stimuli are reported to influence chondrocyte metabolism and may be utilized for regenerative medical approaches. In this review article, we summarize the most relevant stimuli and describe how ion channels may contribute to cartilage homeostasis, with special emphasis on intracellular signaling pathways. We specifically focus on the role of calcium signaling as an essential mechanotransduction component and highlight the role of phosphatase signaling in this context.

Low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments affect degeneration of cultured articular cartilage explants

PURPOSE

Articular cartilage has some capacity for self-repair. Clinically used low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments were compared in their potency to prevent degeneration using an explant model of porcine cartilage.

METHODS

Explants of porcine cartilage and human osteoarthritic cartilage were cultured for four weeks and subjected to daily LIPUS or PEMF treatments. At one, two, three and four weeks follow-up explants were prepared for histological assessment or gene expression (porcine only).

RESULTS

Non-treated porcine explants showed signs of atrophy of the superficial zone starting at one week. Treated explants did not. In LIPUS-treated explants cell clusters were observed. In PEMF-treated explants more hypertrophic-like changes were observed at later follow up. Newly synthesized tissue was present in treated explants. Gene expression profiles did indicate differences between the two methods. Both methods reduced expression of the aggrecan and collagen type II gene compared to the control. LIPUS treatment of human cartilage samples resulted in a reduction of degeneration according to Mankin scoring. PEMF treatment did not.

CONCLUSIONS

LIPUS or PEMF prevented degenerative changes in pig knee cartilage explants. LIPUS reduced degeneration in human cartilage samples. LIPUS treatment seems to have more potency in the treatment of osteoarthritis than PEMF treatment.

Pulsed electromagnetic fields stimulate osteogenic differentiation in human bone marrow and adipose tissue derived mesenchymal stem cells

Pulsed electromagnetic fields (PEMFs) play a regulatory role on osteoblast activity and are clinically beneficial during fracture healing. Human mesenchymal stem cells (MSCs) derived from different sources have been extensively used in bone tissue engineering. Compared with MSCs isolated from bone marrow (BMSCs), those derived from adipose tissue (ASCs) are easier to obtain and available in larger amounts, although they show a less osteogenic differentiation potential than BMSCs. The hypothesis tested in this study was to evaluate whether PEMFs favor osteogenic differentiation both in BMSCs and in ASCs and to compare the role of PEMFs alone and in combination with the biochemical osteogenic stimulus bone morphogenetic protein (BMP)-2. Early and later osteogenic markers, such as alkaline phosphatase (ALP) activity, osteocalcin levels, and matrix mineralization, were analyzed at different times during osteogenic differentiation. Results showed that PEMFs induced osteogenic differentiation by increasing ALP activity, osteocalcin, and matrix mineralization in both BMSCs and ASCs, suggesting that PEMF activity is maintained during the whole differentiation period. The addition of BMP-2 in PEMF exposed cultures further increased all the osteogenic markers in BMSCs, while in ASCs, the stimulatory role of PEMFs was independent of BMP-2. Our results indicate that PEMFs may stimulate an early osteogenic induction in both BMSCs and ASCs and they suggest PEMFs as a bioactive factor to enhance the osteogenesis of ASCs, which are an attractive cell source for clinical applications. In conclusion, PEMFs may be considered a possible tool to improve autologous cell-based regeneration of bone defects in orthopedics.

In vivo effect of two different pulsed electromagnetic field frequencies on osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by fibrillation, reduced cartilage thickness and subchondral bone sclerosis. There is evidence that pulsed electromagnetic fields (PEMFs) counteract OA progression, but the effect of two different PEMF frequencies has not yet been shown. The aim of this study was to test the effectiveness of PEMFs at two different frequencies (37 and 75 Hz) in a late OA stage in 21-month-old Guinea pigs. After 3 months of 6 h/day PEMF stimulation, histological and histomorphometric analyses of the knees were performed. At both frequencies, PEMFs significantly reduced histological cartilage score, fibrillation index (FI), subchondral bone thickness (SBT) and trabecular number (Tb.N) and increased trabecular thickness (Tb.Th) and separation (Tb.Sp) in comparison to the not treated SHAM group. However, PEMFs at 75 Hz produced significantly more beneficial effects on the histological score and FI than 37 Hz PEMFs. At 75 Hz, PEMFs counteracted cartilage thinning as demonstrated by a significantly higher cartilage thickness values than either those of the SHAM or 37 Hz PEMF-treated groups. Although in severe OA both PEMF frequencies were able to limit its progression, 75 Hz PEMF stimulation achieved the better results.

Symptomatic Early Osteoarthritis of the Knee Treated With Pulsed Electromagnetic Fields: Two-Year Follow-up

OBJECTIVE

In vitro and in vivo studies have proven a pro-anabolic and anti-catabolic activity within cartilage with the use of pulsed electromagnetic fields (PEMFs). This has piqued interest of sports physicians for its use in the treatment of early osteoarthritis (OA). The aim was to determine if the use of PEMFs in patients with early OA of the knee would lead to an improved clinical outcome.

STUDY DESIGN

Prospective case series.

METHODS

Twenty-two patients aged between 30 and 60 years who underwent treatment with PEMFs (4-hour treatment per day, duration 45 days) were included. All patients presented with symptomatic early OA with grade 0-2 changes (Kellgren-Lawrence classification) at the pretreatment evaluation. Patients were evaluated before treatment, at 1- and 2-year follow-up using visual analogue scale for pain, International Knee Documentation Committee objective, Tegner, and Knee Injury and Osteoarthritis Outcome Scores.

RESULTS

A significant improvement in all scores was observed at 1-year follow-up (P = 0.008). At 2-year follow-up, results deteriorated but were still superior to pretreatment levels (P = 0.02). No adverse reactions or side effects were seen.

CONCLUSIONS

This study showed that the use of PEMFs in patients with symptomatic early OA of the knee led to significant improvement in symptoms, knee function, and activity at 1-year follow-up. There was a significant decline in all the scores at 2-year follow-up.

Effect of pulsed electromagnetic field therapy in patients undergoing total knee arthroplasty: a randomised controlled trial

Purpose

It has been reported that even one year after total knee arthroplasty (TKA), a relevant percentage of patients does not attain complete recovery and indicate unfavourable long-term pain outcome. We compared the clinical outcome of 33 patients undergoing TKA randomly assigned to the control or the pulsed electromagnetic field group (I-ONE therapy).

Methods

I-ONE therapy was administered postoperatively four hours per day for 60 days. Patients were assessed before surgery and then at one, two and six months postoperatively using international scores.

Results

One month after TKA, pain, knee swelling and functional score were significantly better in the treated compared with the control group. Pain was still significantly lower in the treated group at the six month follow-up. Three years after surgery, severe pain and occasional walking limitations were reported in a significantly lower number of patients in the treated group.

Conclusions

Advantages deriving from early control of joint inflammation may explain the maintenance of results at follow-up. I-ONE therapy should be considered an effective completion of the TKA procedure.

Influence of extremely low frequency, low energy electromagnetic fields and combined mechanical stimulation on chondrocytes in 3-D constructs for cartilage tissue engineering

Articular cartilage, once damaged, has very low regenerative potential. Various experimental approaches have been conducted to enhance chondrogenesis and cartilage maturation. Among those, non-invasive electromagnetic fields have shown their beneficial influence for cartilage regeneration and are widely used for the treatment of non-unions, fractures, avascular necrosis and osteoarthritis. One very well accepted way to promote cartilage maturation is physical stimulation through bioreactors. The aim of this study was the investigation of combined mechanical and electromagnetic stress affecting cartilage cells in vitro. Primary articular chondrocytes from bovine fetlock joints were seeded into three-dimensional (3-D) polyurethane scaffolds and distributed into seven stimulated experimental groups. They either underwent mechanical or electromagnetic stimulation (sinusoidal electromagnetic field of 1 mT, 2 mT, or 3 mT; 60 Hz) or both within a joint-specific bioreactor and a coil system. The scaffold-cell constructs were analyzed for glycosaminoglycan (GAG) and DNA content, histology, and gene expression of collagen-1, collagen-2, aggrecan, cartilage oligomeric matrix protein (COMP), Sox9, proteoglycan-4 (PRG-4), and matrix metalloproteinases (MMP-3 and -13). There were statistically significant differences in GAG/DNA content between the stimulated versus the control group with highest levels in the combined stimulation group. Gene expression was significantly higher for combined stimulation groups versus static control for collagen 2/collagen 1 ratio and lower for MMP-13. Amongst other genes, a more chondrogenic phenotype was noticed in expression patterns for the stimulated groups. To conclude, there is an effect of electromagnetic and mechanical stimulation on chondrocytes seeded in a 3-D scaffold, resulting in improved extracellular matrix production.