Macroscopic and histological effects of magnetic field exposition in the process of tissue reparation in Wistar rats

Progress in the development of piezoelectric biomaterials for tissue remodeling

Piezoelectric biomaterials have demonstrated significant potential in the past few decades to heal damaged tissue and restore cellular functionalities. Herein, we discuss the role of bioelectricity in tissue remodeling and explore ways to mimic such tissue-like properties in synthetic biomaterials. In the past decade, biomedical engineers have adopted emerging functional biomaterials-based tissue engineering approaches using innovative bioelectronic stimulation protocols based on dynamic stimuli to direct cellular activation, proliferation, and differentiation on engineered biomaterial constructs. The primary focus of this review is to discuss the concepts of piezoelectric energy harvesting, piezoelectric materials, and their application in soft (skin and neural) and hard (dental and bone) tissue regeneration. While discussing the prospective applications as an engineered tissue, an important distinction has been made between piezoceramics, piezopolymers, and their composites. The superiority of piezopolymers over piezoceramics to circumvent issues such as stiffness mismatch, biocompatibility, and biodegradability are highlighted. We aim to provide a comprehensive review of the field and identify opportunities for the future to develop clinically relevant and state-of-the-art biomaterials for personalized and remote health care.

Static magnetic fields in regenerative medicine

All organisms on Earth live in the weak but ubiquitous geomagnetic field. Human beings are also exposed to magnetic fields generated by multiple sources, ranging from permanent magnets to magnetic resonance imaging (MRI) in hospitals. It has been shown that different magnetic fields can generate various effects on different tissues and cells. Among them, stem cells appear to be one of the most sensitive cell types to magnetic fields, which are the fundamental units of regenerative therapies. In this review, we focus on the bioeffects of static magnetic fields (SMFs), which are related to regenerative medicine. Most reports in the literature focus on the influence of SMF on bone regeneration, wound healing, and stem cell production. Multiple aspects of the cellular events, including gene expression, cell signaling pathways, reactive oxygen species, inflammation, and cytoskeleton, have been shown to be affected by SMFs. Although no consensus yet, current evidence indicates that moderate and high SMFs could serve as a promising physical tool to promote bone regeneration, wound healing, neural differentiation, and dental regeneration. All in vivo studies of SMFs on bone regeneration and wound healing have shown beneficial effects, which unravel the great potential of SMFs in these aspects. More mechanistic studies, magnetic field parameter optimization, and clinical investigations on human bodies will be imperative for the successful clinical applications of SMFs in regenerative medicine.

Chitosan sponges loaded with metformin and microalgae as dressing for wound healing: A study in diabetic bio-models

Among the conditions caused by diabetes, the diabetic foot is a significant public health problem due to its delayed healing process. That makes it essential to design, manufacture, and apply auxiliary dressings during healing. In this work, chitosan sponges were developed and evaluated as wound dressings. Metformin, fucoidan, and exopolysaccharide from Porphyridium purpureum algae were loaded into the sponges and studied as healing promoters. The composite sponges were physicochemically, morphologically, and thermally characterized, allowing us to determine the chemical mechanisms involved in the sponge formation. The mechanical analysis demonstrated that sponge composites have shape memory and good mechanical performance under compression stress, showing a compressive strength above 30 kPa. These results correlated with the materials' porosity, influencing the swelling capacity that reached a maximum of 70 %. The morphology of materials was observed by SEM, resulting in folded films with surface porosity. The results of the biocompatibility tests confirmed that the materials are not cytotoxic or hemolytic and have good antibacterial activity. In vivo wound healing evaluation showed that metformin-loaded chitosan sponges regenerated skin tissue after 21 days of treatment, highlighting the rate of healing provided when exopolysaccharide was added to promote tissue regeneration, which can be corroborated by histological analysis. These results make chitosan sponge compounds promising dressings for diabetic foot wound treatment.

Static magnetic field blocked alprazolam-induced behavior of Wistar rats in the elevated plus-maze test

Studies have shown that psychotropic drugs change rat behavior in the elevated plus-maze test (EPM). This study investigated whether static magnetic fields could alter alprazolam-induced rat behavior in the EPM. 66 male Wistar rats (270-300 g weight) were assigned to one of the following groups: Sham Magnetic + Saline (SMS), North Pole + Saline (NPS), South Pole + Saline (SPS), Sham magnetic + alprazolam (SMA), NP + alprazolam (NPA), and SP + alprazolam (SPA). After five days of static magnetic stimulation (3200 Gauss), they received alprazolam or saline (1 mg/kg), and their behavior was evaluated. Two-way ANOVA and Holm-Sidak post-hock were used, with a significant P value of <0.05. The SMA and NPA groups showed an increased number of entries and time in the open arms compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 6.43 and F(2,61) = 3.72, respectively]. The SMA and NPA groups showed increased head dipping and end-arm activity compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 3.37 and [F(2,61) = 4.72, respectively]. These results show that the south magnetic pole of a static magnetic field blocked the alprazolam effect in the space-time variables of the open arms and ethological anxiolytic-like behavior in the EPM.

Toxicity, Anti-Inflammatory, and Antioxidant Activities of Cubiu (Solanum sessiliflorum) and Its Interaction with Magnetic Field in the Skin Wound Healing

Cubiu, an Amazonian fruit, is widely used as food and popular treatment for pathologies that present an inflammatory pattern, such as skin wound healing. However, there is still no confirmation in the scientific literature about the safety profile, as well as the anti-inflammatory, antioxidant, and healing actions of cubiu. This study is divided into two experimental protocols using Wistar rats. Thus, the first objective (protocol 1) of this study was to evaluate the toxicity of an oral administration of cubiu extract at different doses for 28 days. The macroscopic and microscopic analyses of the liver and kidney were performed, and the following analysis was determined in plasma: glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, gamma-glutamyl transpeptidase, glucose, triglycerides, total cholesterol, urea, creatinine, and uric acid. After, we conducted the second protocol aimed to establish the potential antioxidant and anti-inflammatory capacity of cubiu and its interaction with magnetic field in skin wound healing. On days 3, 7, and 14 of treatment, skin and blood samples were collected and analyzed: the oxidative stress biomarkers (reactive substances to thiobarbituric acid, nonprotein thiols, superoxide dismutase, catalase, and glutathione S-transferase), myeloperoxidase enzymatic activity, and cytokines levels (interleukin 1, interleukin 6, interleukin 10, and tumor necrosis factor-alpha). The cubiu has shown to be safe and nontoxic. Both cubiu and magnetic field promoted decreased levels of proinflammatory and prooxidant biomarkers (interleukin 1, interleukin 6, tumor necrosis factor-alpha, and reactive substances to thiobarbituric acid), as well as increased levels of anti-inflammatory and antioxidant biomarkers (interleukin 10, nonprotein thiols, and superoxide dismutase), with greater potential when treatments are used in association. Thus, cubiu promotes antioxidant and anti-inflammatory action in skin wound healing, while also improving results of the conventional treatment for skin healing (magnetic field) when used in association.

Effect of Magnetohydrodynamic on Cutaneous Wound Healing in Rat Model

Background: Exogenous electrical stimulation of the skin may mimic its endogenous bioelectric currents. In this study, a combination of direct current (DC) and magnetic field (MF) was investigated in the excision of the rat wound model. Methods: A circular wound was created on the posterior of the neck, and an electrode was fixed in the wound center. Rats were divided into sham, DC (600 µA), MF (~0.8 T), and magnet-direct current (MDC) groups. The study was conducted in 14 days with 20-min treatment daily. Results: The DC and MDC groups had higher healing percentages (P < 0.01) with mean differences of -13.42 and -15.63, respectively. Direct current on days 2, 5, and 6, and MDC on days 8, 9, 10, 11, 12, and 13 showed higher wound closing. In the DC-treated group, angiogenesis was improved on day 7. In MDC-treated rats, angiogenesis and fibroplasia were improved on day 13. The MF and MDC groups had lower granulation thicknesses on day 7. Granulation thickness increased on day 13 in the MF and MDC groups, while it decreased in the DC group. Direct current treatment improved healing in the first half of the study period, whereas MDC enhanced it in the second half, overtaking DC. From day 7, the magnet group started to overtake the control group slightly in the last four days. Conclusions: To accelerate wound healing, we suggest applying DC in the first days of wounding and MDC in the following days.

Magnetic fields as a potential therapy for diabetic wounds based on animal experiments and clinical trials

Diabetes mellitus (DM) is a chronic metabolic disorder with various complications that poses a huge worldwide healthcare burden. Wounds in diabetes, especially diabetic foot ulcers (DFUs), are difficult to manage, often leading to prolonged wound repair and even amputation. Wound management in people with diabetes is an extremely clinical and social concern. Nowadays, physical interventions gain much attention and have been widely developed in the fields of tissue regeneration and wound healing. Magnetic fields (MFs)-based devices are translated into clinical practice for the treatment of bone diseases and neurodegenerative disorder. This review attempts to give insight into the mechanisms and applications of MFs in wound care, especially in improving the healing outcomes of diabetic wounds. First, we discuss the pathological conditions associated with chronic diabetic wounds. Next, the mechanisms involved in MFs' effects on wounds are explored. At last, studies and reports regarding the effects of MFs on diabetic wounds from both animal experiments and clinical trials are reviewed. MFs exhibit great potential in promoting wound healing and have been practised in the management of diabetic wounds. Further studies on the exact mechanism of MFs on diabetic wounds and the development of suitable MF-based devices could lead to their increased applications into clinical practice.

Transcriptome Analysis Reveals the Negative Effect of 16 T High Static Magnetic Field on Osteoclastogenesis of RAW264.7 Cells

The magnetic field is the most common element in the universe, and high static magnetic field (HiSMF) has been reported to act as an inhibited factor for osteoclasts differentiation. Although many studies have indicated the negative role of HiSMF on osteoclastogenesis of RANKL-induced RAW264.7 cells, the molecular mechanism is still elusive. In this study, the HiSMF-retarded cycle and weakened differentiation of RAW264.7 cells was identified. Through RNA-seq analysis, RANKL-induced RAW264.7 cells under HiSMF were analysed, and a total number of 197 differentially expressed genes (DEGs) were discovered. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that regulators of cell cycle and cell division such as Bub1b, Rbl1, Ube2c, Kif11, and Nusap1 were highly expressed, and CtsK, the marker gene of osteoclastogenesis was downregulated in HiSMF group. In addition, pathways related to DNA replication, cell cycle, and metabolic pathways were significantly inhibited in the HiSMF group compared to the Control group. Collectively, this study describes the negative changes occurring throughout osteoclastogenesis under 16 T HiSMF treatment from the morphological and molecular perspectives. Our study provides information that may be utilized in improving magnetotherapy on bone disease.

Combination Therapy Comprising a Static Magnetic Field with Contractility Improves Skin Wounds

Cutaneous wounds can present significant clinical problems because of abnormal healing after deep dermal damage. Despite technical advances in wound care, there are still unmet needs that result from inefficient treatment. In this study, we aimed to improve skin wound healing using a contractibility band with static magnetic field (SMF), termed a magnetic band (Mb). To examine the effect of the Mb on wound healing, full-thickness 15 × 35 mm excision wounds were surgically created on the dorsum of rats. An elastic and contractile band (nontreatment), or one neodymium magnet (Nd-1) or two magnets with an elastic and contractile band (Nd-2) were topically applied to the wound daily and the wound size was measured from day 1 to 7 after surgery. Nd-2 showed a significant (95%) reduction in the wound size on day 3. Histological analysis showed that proinflammatory cytokine levels were diminished by Nd-2, and granulation tissue and microvessels were increased compared with those in the sham group. During Mb-induced wound healing, apoptosis was significantly reduced and matrix remodeling-related factors were initially regulated. The results suggest that combination therapy comprising an SMF and an elastic and contractile band could be a promising tool to heal cutaneous wounds rapidly.

Effects of extremely low-frequency magnetotherapy on proliferation of human dermal fibroblasts

Extremely low-frequency electromagnetic fields (ELF-EMFs) applied in magnetotherapy have frequency lower than 100 Hz and magnetic field intensity ranging from 0.1 to 20 mT. For many years, the use of magnetotherapy in clinics has been increasing because of its beneficial effects in many processes, e.g., skin diseases, inflammation and bone disorders. However, the understanding of the microscopic mechanisms governing such processes is still lacking and the results of the studies on the effects of ELF-EMFs are controversial because effects derive from different conditions and from intrinsic responsiveness of different cell types.In the present study, we studied the biological effects of 1.5 h exposure of human dermal fibroblasts to EMFs with frequencies of 5 and 50 Hz and intensity between 0.25 and 1.6 mT. Our data showed that the magnetic treatment did not produce changes in cell viability, but gave evidence of a sizeable decrease in proliferation at 24 h after treatment. In addition, immunofluorescence experiments displayed an increase in tubulin expression that could foreshadow changes in cell motility or morphology. The decrease in proliferation with unchanged viability and increase in tubulin expression could be consistent with the triggering of a transdifferentiation process after the exposure to ELF-EMFs.

Proliferation and differentiation of rat bone marrow stem cells by 400μT electromagnetic field

The interaction between environment electromagnetic field (EMF) and cells can effect on various physiological processes. EMF as an external inducing factor, could effect on proliferation or differentiation of cells. The purpose of this study was to evaluate the influence of the electromagnetic field on the viability, proliferation and differentiation rate of bone marrow stem cells (BMSCs) to neuron. BMSCs were obtained from 42 adult male rats. The cells incubated and cultured in 96-wells and 6-wells plates and exposed to electromagnetic field (40 or 400μT) with a selected waveform: AC (alternative current), rectified half wave (RHW) and rectified full wave (RFW), for a week. To assess the viability and proliferation rate of treated cells, MTT assay was done, and then immunocytochemistry staining Neu N was used to evaluate cell differentiation to neuron. Results showed that EMF decreases the viability and proliferation in treated groups. But in AC group's reduction was significant. Minimum viability and proliferation rate was observed in RHW 400μT group compared with sham. Immunocytochemistry showed that EMF can induce BMSC differentiation into neuron in AC 400μT and RFW 400μT. Evidences of this research support the hypothesis that EMF can induce differentiation of BMSCs to neuron.

Estimation of changes in fitness components and antioxidant defense of Drosophila subobscura (Insecta, Diptera) after exposure to 2.4 T strong static magnetic field

As an ecological factor, a magnetic field can affect insects causing a wide range of responses. The main purpose of this study was to analyze the fitness components (postembryonic development and viability of individuals) and the antioxidant defense (superoxide dismutase, catalase, and total glutathione) in laboratory strains of Drosophila subobscura, originating from oak and beech forests after exposure to the strong static magnet (2.4 T, VINCY Cyclotron magnet). The first instar larvae were placed near the north pole (N group) or the south pole (S group) of the magnet for 2 h. Oak and beech populations of D. subobscura had longer development time and lower viability in N and S groups compared to controls. These differences were significant only in S group of oak population and in N group of beech population. Total glutathione content was significantly decreased in both exposed groups of oak population, while catalase activity was significantly increased in both exposed groups of beech population. Being significantly decreased in both exposed groups of oak population and significantly increased in S group of beech population in comparison to controls, superoxide dismutase activity was observed in different values. According to the results, it can be stated that applied static magnetic field could be considered a potential stressor influencing the fitness components and antioxidant defense in Drosophila flies.

Experimental model for ELF-EMF exposure: Concern for human health

Low frequency (LF) electromagnetic fields (EMFs) are abundantly present in modern society and in the last 20 years the interest about the possible effect of extremely low frequency (ELF) EMFs on human health has increased progressively. Epidemiological studies, designed to verify whether EMF exposure may be a potential risk factor for health, have led to controversial results. The possible association between EMFs and an increased incidence of childhood leukemia, brain tumors or neurodegenerative diseases was not fully elucidated. On the other hand, EMFs are widely used, in neurology, psychiatry, rheumatology, orthopedics and dermatology, both in diagnosis and in therapy. In vitro studies may help to evaluate the mechanism by which LF-EMFs affect biological systems. In vitro model of wound healing used keratinocytes (HaCaT), neuroblastoma cell line (SH-SY5Y) as a model for analysis of differentiation, metabolism and functions related to neurodegenerative processes, and monocytic cell line (THP-1) was used as a model for inflammation and cytokines production, while leukemic cell line (K562) was used as a model for hematopoietic differentiation. MCP-1, a chemokine that regulates the migration and infiltration of memory T cells, natural killer (NK), monocytes and epithelial cells, has been demonstrated to be induced and involved in various diseases. Since, varying the parameters of EMFs different effects may be observed, we have studied MCP-1 expression in HaCaT, SH-SY5Y, THP-1 and K562 exposed to a sinusoidal EMF at 50 Hz frequency with a flux density of 1 mT (rms). Our preliminary results showed that EMF-exposure differently modifies the expression of MCP-1 in different cell types. Thus, the MCP-1 expression needs to be better determined, with additional studies, with different parameters and times of exposure to ELF-EMF.

Effect of static magnetic field on experimental dermal wound strength

Context:

An animal model.

Aim:

We sought to evaluate the effect of static magnetic fields on cutaneous wound healing.

Materials and Methods:

Male Wistar rats were used. Wounds were created on the backs of all rats. Forty of these animals (M group) had NeFeB magnets placed in contact with the incisions, either parallel (Pa) and perpendicular (Pr) to the incision. The other 40 animals (sham [S] group) had nonmagnetized NeFeB bars placed in the same directions as the implanted animals. Half of the animals in each group were killed and assessed for healing on postoperative day 7 and the other half on postoperative day 14. The following assessments were done: gross healing, mechanical strength, and histopathology.

Statistical Analysis Used:

Intergroup differences were compared by using the Mann-Whitney U or t test. Values for P less than 0.05 were accepted as significant.

Results and Conclusions:

There were no differences between the magnetic and sham animals with respect to gross healing parameters. The mechanical strength was different between groups. On postoperative day 14, the MPr14 had significantly higher scores than the other groups. When static, high-power, magnetic fields are placed perpendicular to the wound, increased wound healing occurs in the skin of the experimental model.

Effects of 180 mT static magnetic fields on diabetic wound healing in rats

Diabetic wound (DW) problems are becoming a formidable clinical challenge due to the sharp increase in the diabetic population and the high incidence of DW. Static magnetic field (SMF) therapy, an inexpensive and accessible noninvasive method, has been proven to be effective on various tissue repairs. However, the issue of the therapeutic effect of SMF on DW healing has never been investigated. The objective of this study was to systematically evaluate the effect of a 180 mT moderate-intensity gradient SMF on DW healing in streptozotocin-induced diabetic rats. Forty-eight 3-month-old male Sprague-Dawley rats (32 diabetic and 16 non-diabetic rats) were assigned to three equal groups: normal wound, DW, and DW + SMF groups. An open circular wound with 1.5 cm diameter was created in the dorsum. The wound was covered with a dressing and the magnet was fixed on top of the dressing. On days 5, 12, and 19, four rats of each group were euthanized and gross wound area, histology and tensile strength were evaluated. The wound area determination suggested that SMF significantly increased the healing rate and reduced the gross healing time. This result was further confirmed by histological observations. The wound tensile strength, reflecting the amount and quality of collagen deposition, increased to a larger extent in the DW + SMF group on days 12 and 19 compared with the DW group. The results indicated that 180 mT SMF presented a beneficial effect on DW healing, and implied the clinical potential of SMF therapy in accelerating DW repair and releasing the psychological and physical burdens of diabetic patients.