Enhanced responsiveness to parathyroid hormone and induction of functional differentiation of cultured rabbit costal chondrocytes by a pulsed electromagnetic field

Promising application of Pulsed Electromagnetic Fields (PEMFs) in musculoskeletal disorders

Increasing evidence suggests that an exogenous electromagnetic field might be involved in many biologic processes which are of great importance for therapeutic interventions. Pulsed electromagnetic fields (PEMFs) are known to be a noninvasive, safe and effective therapy agent without apparent side effects. Numerous studies have shown that PEMFs possess the potential to become a stand-alone or adjunctive treatment modality for treating musculoskeletal disorders. However, several issues remain unresolved. Prior to their widely clinical application, further researches from well-designed, high-quality studies are still required to standardize the treatment parameters and derive the optimal protocol for health-care decision making. In this review, we aim to provide current evidence on the mechanism of action, clinical applications, and controversies of PEMFs in musculoskeletal disorders.

Stem cells and physical energies: can we really drive stem cell fate?

Adult stem cells are undifferentiated elements able to self-renew or differentiate to maintain tissue integrity. Within this context, stem cells are able to divide in a symmetric fashion, feature characterising all the somatic cells, or in an asymmetric way, which leads daughter cells to different fates. It is worth highlighting that cell polarity have a critical role in regulating stem cell asymmetric division and the proper control of cell division depends on different proteins involved in cell development, differentiation and maintenance of tissue homeostasis. Moreover, the interaction between cells and the extracellular matrix are crucial in influencing cell behavior, included in terms of mechanical properties as cytoskeleton plasticity and remodelling, and membrane tension. Finally, the activation of specific transcriptional program and epigenetic modifications contributes to cell fate determination, through modulation of cellular signalling cascades. It is well known that physical and mechanical stimuli are able to influence biological systems, and in this context, the effects of electromagnetic fields (EMFs) have already shown a considerable role, even though there is a lack of knowledge and much remains to be done around this topic. In this review, we summarize the historical background of EMFs applications and the main molecular mechanism involved in cellular remodelling, with particular attention to cytoskeleton elasticity and cell polarity, required for driving stem cell behavior.

MiR200 and miR302: Two Big Families Influencing Stem Cell Behavior

In this review, we described different factors that modulate pluripotency in stem cells, in particular we aimed at following the steps of two large families of miRNAs: the miR-200 family and the miR-302 family. We analyzed some factors tuning stem cells behavior as TGF-β, which plays a pivotal role in pluripotency inhibition together with specific miRNAs, reactive oxygen species (ROS), but also hypoxia, and physical stimuli, such as ad hoc conveyed electromagnetic fields. TGF-β plays a crucial role in the suppression of pluripotency thus influencing the achievement of a specific phenotype. ROS concentration can modulate TGF-β activation that in turns down regulates miR-200 and miR-302. These two miRNAs are usually requested to maintain pluripotency, while they are down-regulated during the acquirement of a specific cellular phenotype. Moreover, also physical stimuli, such as extremely-low frequency electromagnetic fields or high-frequency electromagnetic fields conveyed with a radioelectric asymmetric conveyer (REAC), and hypoxia can deeply influence stem cell behavior by inducing the appearance of specific phenotypes, as well as a direct reprogramming of somatic cells. Unraveling the molecular mechanisms underlying the complex interplay between externally applied stimuli and epigenetic events could disclose novel target molecules to commit stem cell fate.

Electromagnetic fields mediate efficient cell reprogramming into a pluripotent state

Life on Earth is constantly exposed to natural electromagnetic fields (EMFs), and it is generally accepted that EMFs may exert a variety of effects on biological systems. Particularly, extremely low-frequency electromagnetic fields (EL-EMFs) affect biological processes such as cell development and differentiation; however, the fundamental mechanisms by which EMFs influence these processes remain unclear. Here we show that EMF exposure induces epigenetic changes that promote efficient somatic cell reprogramming to pluripotency. These epigenetic changes resulted from EMF-induced activation of the histone lysine methyltransferase Mll2. Remarkably, an EMF-free system that eliminates Earth's naturally occurring magnetic field abrogates these epigenetic changes, resulting in a failure to undergo reprogramming. Therefore, our results reveal that EMF directly regulates dynamic epigenetic changes through Mll2, providing an efficient tool for epigenetic reprogramming including the acquisition of pluripotency.

Stimulation of ankle cartilage: other emerging technologies (cellular, electricomagnetic, etc.)

Advances in understanding age-related changes in articular cartilage, joint homeostasis, the natural healing process after cartilage injury, and improved standards for evaluation of a joint surface made the ultimate goal of cartilage repair a possibility. New strategies for enhancement of articular cartilages' limited healing potential and biologic regeneration include advances in tissue engineering and the use of electromagnetic fields. This article reviews developments in basic science and clinical research made with these emerging technologies concerning treatment of articular cartilage defects and treatment of osteoarthritis of the ankle.

Electromagnetic field and osteogenesis

<zakljucak> Poslednjih 50 godina postignuti su odlicni rezultati primenom elektrobioloske stimulacije osteogeneze. Precizno objasnjenje mehanizma dejstva EMP jos uvek nije dato, sto je jedan od razloga razlicitih pristupa i rezultata lecenja prema iskustvima klinicara i eksperimentnih studija. Uzimajuci u obzir studije sa dobrim bioloskim protokolom, preciznom dozimetrijom i definisanim eksperimentnim uslovima, stimulacija osteogeneze EMP ostace aktuelna i u buducnosti.

The role of electrical stimulation in bone repair

Electric and electromagnetic fields regulate extra-cellular matrix synthesis and stimulate repair of fractures and nonunions. Studies of electric and electromagnetic fields suggest they (1) regulate proteoglycan and collagen synthesis and increase bone formation in models of endochondral ossification, (2) accelerate bone formation and repair, (3) increase union rates in fractures previously refractory to healing, and (4) produce results equivalent to bone grafts. Electric and electromagnetic fields regulate the expression of genes in connective tissue cells for extra-cellular matrix proteins, which results in an increase in cartilage and bone. They also increase gene expression for and synthesis of growth factors, which may be an intermediary mechanism of activity and may amplify field effects through autocrine and paracrine signaling.

Electromagnetic fields for bone healing

Electrical stimulation has been applied in a number of different ways to influence tissue healing. Most of the early work was carried out by orthopedic surgeons looking for new ways of enhancing fracture healing, particularly those fractures that had developed into nonunions. Electrical energy can be supplied to a fracture by direct application of electrodes or inducing current by use of pulsed electromagnetic field or capacitive coupling. Many of these techniques have not been standardized, so interpretation of the literature can be difficult and misleading. Despite this, there have been a few good laboratory and clinical studies to investigate the effect of electrical stimulation on fracture healing, which are reviewed. These do not permit recommendation or rejection of the technique per se; however, there is some room for optimism. The authors present some of the guidelines for using this treatment modality but suggest that all treatment should be carried out as part of a clinical trial in order to generate reliable data.

Stimulation of growth factor synthesis by electric and electromagnetic fields

Biophysical input, including electric and electromagnetic fields, regulate the expression of genes in connective tissue cells for structural extracellular matrix (ECM) proteins resulting in an increase in cartilage and bone production. In in vivo models and clinical situations, this can be manifested as enhanced repair and a gain in mechanical properties of the repairing tissues. The mechanisms by which cell functions are regulated by biophysical input is the subject of this review. Biophysical interactions of electric and electromagnetic fields at the cell membrane are not well understood and require considerable additional study. We review information on transmembrane signaling, channel activation and receptor stimulation or blockade. Understanding physical interactions and transmembrane signaling will most likely be necessary to establish dosing paradigms and improve therapeutic efficacy. Considerable information has been generated on an intermediary mechanism of activity - growth factor stimulation. Electric and electromagnetic fields increase gene expression for, and synthesis of, growth factors and this may function to amplify field effects through autocrine and paracrine signaling. Electric and electromagnetic fields can produce a sustained upregulation of growth factors, which enhance, but do not disorganize endochondral bone formation. Progress in the areas of signal transduction and growth factor synthesis is very rapid and future directions are suggested.

Effects of extremely low frequency electromagnetic field (EMF) on collagen type I mRNA expression and extracellular matrix synthesis of human osteoblastic cells

Human osteoblastic cells were grown in a three-dimensional (3-D) cell culture model and used to test the effects of a 20 Hz sinusoidal electromagnetic field (EMF; 6 mT and 113 mV/cm max) on collagen type I mRNA expression and extracellular matrix formation in comparison with the effects of growth factors. The cells were isolated from trabecular bone of a healthy individual (HO-197) and from a patient presenting with myositis ossificans (MO-192) and grown in a collagenous sponge-like substrate. Maximal enhancement of collagen type I expression after EMF treatment was 3.7-fold in HO-197 cells and 5.4-fold in MO-192 cells. Similar enhancement was found after transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) treatment. Combined treatment of the cells with EMF and the two growth factors TGF-beta and IGF-I did not act synergistically. MO-192 cells produced an osteoblast-characteristic extracellular matrix containing collagen type I, alkaline phosphatase, and osteocalcin, together with collagen type III, TP-1, and TP-3, two epitopes of an osteoblastic differentiation marker. The data suggest that the effects of EMFs on osteoblastic differentiation are comparable to those of TGF-beta and IGF-I. We conclude that EMF effects in the treatment of skeletal disorders and in orthopedic adjuvant therapy are mediated via enhancement of collagen type I mRNA expression, which may lead to extensive extracellular matrix synthesis.

A double-blind study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusions

STUDY DESIGN

A randomized double-blind prospective comparison with a placebo control. This report of the results is the first in an ongoing study.

OBJECTIVES

To evaluate the effect of noninvasive capacitively coupled electrical stimulation on the success rate of lumbar spine fusion surgery, and to compare active with placebo stimulators as adjuncts to contemporary fusion techniques.

SUMMARY OF BACKGROUND DATA

Previous studies have established the effectiveness of direct current and electromagnetic field stimulation as adjuncts for some forms of spinal fusion. None of the previous placebo-controlled studies on external bone stimulation included posterolateral fusion techniques, and most were conducted with prior generations of internal fixation hardware.

METHODS

The investigation was conducted by 28 U.S. surgeons. Patients with a primary diagnosis of degenerative disc disease with or without other degenerative changes were selected. The study protocol defined success as a clinical outcome rated as excellent or good and a fusion documented as solid by both the investigator and the blinded independent radiologist. Disagreements on radiographic success were resolved by a second blinded independent reviewer.

RESULTS

For the 179 patients who completed treatment and evaluation, the overall protocol success rate (both clinical and radiographic results rated as successes) was 84.7% for the active patients and 64.9% for the placebo patients. This difference is highly significant according to the Yates corrected chi-square test (P = 0.0043). Best improvements in patient outcomes (20% or greater success rate) occurred when active stimulation was used in conjunction with posterolateral fusion (P = 0.006) and when internal fixation also was incorporated (P = 0.013).

DISCUSSION

This study was consistent in that active stimulation improved results for each stratification, although some strata had insufficient numbers of patients for the results to have statistical significance. Improved success rates when capacitively coupled stimulation is added to internal fixation are hypothesized to result from overcoming the biochemical effects of stress shielding.

CONCLUSIONS

Capacitively coupled stimulation is an effective adjunct to primary spine fusion, especially for patients with posterolateral fusion and those with internal fixation.

Pulsed electromagnetic fields preserve proteoglycan composition of extracellular matrix in embryonic chick sternal cartilage

The influence of pulsed electromagnetic fields (PEMF) on proteoglycan composition in cartilage extracellular matrix has been investigated. Day 16 embryonic chick sternal cartilage was explanted to culture and exposed for 3 h per day for 2 days to a repetitive single-pulse PEMF with frequency of 15 Hz and peak magnetic field of 1.25 G. PEMF treatment did not affect cell proliferation, as indicated by [3H]thymidine incorporation, but significantly stimulated the retention of glycosaminoglycans in the explants and reduced the release of glycosaminoglycans into the media. Determination of incorporation of [35S]sulfate and [3H]N-acetylglucosamine into proteoglycans in vitro and breakdown of in ovo labelled [35S]sulfated proteoglycans in vitro showed that PEMF treatment significantly suppressed the synthesis of proteoglycans and the degradation of both newly synthesized and pre-existing proteoglycans. Sepharose CL-2B chromatography demonstrated that PEMF did not affect either the size distribution of newly synthesized and pre-existing [35S]sulfated proteoglycans or their ability to aggregate with hyaluronate. Sepharose CL-6B chromatography followed by cellulose acetate electrophoresis revealed that the chain length and degree of sulfation of [35S]sulfated glycosaminoglycans were identical in control and PEMF-treated cultures. It is concluded that PEMF treatment preserved extracellular matrix integrity of cultured cartilage explants by down-regulating proteoglycan synthesis and degradation in a co-ordinated manner without affecting their gross structural nature.

Pulsed electromagnetic fields influence hyaline cartilage extracellular matrix composition without affecting molecular structure

Pulsed electromagnetic fields (PEMF) influence the extracellular matrix metabolism of a diverse range of skeletal tissues. This study focuses upon the effect of PEMF on the composition and molecular structure of cartilage proteoglycans. Sixteen-day-old embryonic chick sterna were explanted to culture and exposed to a PEMF for 3 h/day for 48 h. PEMF treatment did not affect the DNA content of explants but stimulated elevation of glycosaminoglycan content in the explant and conserved the tissue's histological integrity. The glycosaminoglycans in sterna exposed to PEMF were indistinguishable from those in controls in their composition of chondroitin sulfate resulting from chondroitinase ABC digestion. Specific examination with [35S]-sulfate labels showed that PEMF treatment significantly suppressed both the degradation of pre-existing glycosaminoglycans biosynthetically labeled in ovo and the synthesis of new [35S]-sulfated glycosaminoglycans. The average size and aggregating ability of pre-existing and newly synthesized [35S]-sulfated proteoglycans extracted with 4 M guanidinium chloride from PEMF-treated cartilage explants were identical to controls. The chain length and degree of sulfation of [35S]-sulfated glycosaminoglycans also were identical in control and PEMF-treated cultures. PEMF treatment also reduced the amount of both unlabeled glycosaminoglycans and labeled pre-existing and newly synthesized [35S]-sulfated glycosaminoglycans recovered from the nutrient media. [35S]-Sulfated proteoglycans released to the media of both control and PEMF-treated cultures were mostly degradation products although their glycosaminoglycan chain size was unchanged. These results demonstrate that exposure of embryonic chick cartilage explants to PEMF for 3 h/day maintains a balanced proteoglycan composition by down-regulating its turnover without affecting either molecular structure or function.

Effects of electromagnetic fields on molecules and cells

Evidence suggests that cell processes can be influenced by weak electromagnetic fields (EMFs). EMFs appear to represent a global interference or stress to which a cell can adapt without catastrophic consequences. There may be exceptions to this observation, however, such as the putative role of EMFs as promoters in the presence of a primary tumor initiator. The nature of the response suggests that the cell is viewing EMFs as it would another subtle environmental change. The age and state of the cell can profoundly affect the EMF bioresponse. There is no evidence that direct posttranscription effects occur as a result of EMF exposure. Although transcription alterations occur, no apparent disruption in routine physiological processes such as growth and division is immediately evident. What is usually observed is a transient perturbation followed by an adjustment by the normal homeostatic machinery of the cells. DNA does not appear to be significantly altered by EMF. If EMF exposure is associated with an increased risk of cancer, the paucity of genotoxic effects would support the suggestion that the fields act in tumor promotion rather than initiation. The site(s) and mechanisms of interaction remain to be elaborated. Although there are numerous studies and hypotheses that suggest the membrane represents the primary site of interaction, there are also several different studies showing that in vitro systems, including cell-free systems, are responsive to EMFs. The debate about potential hazards or therapeutic value of weak electromagnetic fields will continue until the mechanism of interaction has been clarified.

Cancer promotion in a mouse-skin model by a 60-Hz magnetic field: II. Tumor development and immune response

This paper describes preliminary findings on the influence of 60-Hz (2-mT) magnetic fields on tumor promotion and co-promotion in the skins of mice. The effect of magnetic fields on natural killer (NK) cell activity in spleen and blood was also examined. Groups of 32 juvenile female mice were exposed to the magnetic field as described in part I. The dorsal skin of all animals was treated with a subthreshold dose of the carcinogen 7,12-dimethyl-benz(a)anthracene (DMBA). One week after the treatment, two groups were sham exposed (group A) or field exposed at 2 mT (group B) 6 h/day for 21 weeks, to test whether the field would act as a tumor promoter. No tumors developed in these two groups of mice. To test whether the magnetic field would modify tumor development by directly affecting tumor growth or by suppressing immune surveillance, two additional groups of mice were treated weekly with the tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA) and then either sham exposed (group C) or field exposed (group D). The time to appearance of tumors was shorter (but not statistically so) in the group exposed to magnetic fields and TPA. Some differences in NK cell activity and spleen size were observed between the sham- and field-exposed groups.