ABSTRACT
Objective: Most people experience bone damage and bone disorders during their lifetimes. The use of autografts is a suitable way for injury recovery and healing. Mesenchymal stem cells [MSCs] are key players in tissue engineering and regenerative medicine. Their proliferation potential and multipotent differentiation ability enable MSCs to be considered as appropriate cells for therapy and clinical applications. Differentiation of stem cells depends on their microenvironment and biophysical stimulations. The aim of this study is to analyze the effects of an electromagnetic field on osteogenic differentiation of stem cells
Materials and Methods: In this experimental animal study, we assessed the effects of the essential parameters of a pulsatile electromagnetic field on osteogenic differentiation. The main purpose was to identify an optimum electromagnetic field for osteogenesis induction. After isolating MSCs from male Wistar rats, passage-3 [P3] cells were exposed to an electromagnetic field that had an intensity of 0.2 millitesla [mT] and frequency of 15 Hz for 10 days. Flow cytometry analysis confirmed the mesenchymal identity of the isolated cells. Pulsatile electromagnetic field-stimulated cells were examined by immunocytochemistry and real-time polymerase chain reaction [PCR]
Results: Electromagnetic field stimulation alone motivated the expression of osteogenic genes. This stimulation was more effective when combined with osteogenic differentiation medium 6 hours per day for 10 days. For the in vivo study, an incision was made in the cranium of each animal, after which we implanted a collagen scaffold seeded with stimulated cells into the animals. Histological analysis revealed bone formation after 10 weeks of implantation
Conclusion: We have shown that the combined use of chemical factors and an electromagnetic field was more effective for inducing osteogenesis. These elements have synergistic effects and are beneficial for bone tissue engineering applications
Subject(s)
Animals, Laboratory , Male , Gene Expression/radiation effects , Mesenchymal Stem Cells/radiation effects , Osteogenesis , Rats, WistarABSTRACT
Background: Extremely low frequency [0-300 Hz] fields from power lines, electronic equipment and medical devices, have been reported to produce various biological effects. Global system for mobile [GSM] is most largely used in everybody's life. This system utilizes a low frequency band as well as a high frequency range of electromagnetic field. This study investigated the effects of 217 Hz electromagnetic field [the modulating signal in GSM] on spatial learning and memory in rat
Methods: Twenty four male Wistar rat [200- 250 g] were randomly divided in to three groups as: test, sham and control. Using a Helmholtz coil system, the test group was exposed to a uniform pulsed EMF of 200 microT [micro Tesla] intensity for 4 h/day for 21 days [2 time in a day]. This procedure was repeated for the sham group but with no field. All groups were trained prior to the day 21 on the 15th day for five days four trial per day in Morris Water-Maze system. Then the probe test was carried out for 60 seconds with no platform
Results: The ANOVA test revealed that no significant differences were found between control and exposed rats in all day of learning acquisition. Also, in probe test for investigating the memory, no significant differences observed. [P
Conclusion: This finding is in consistent with previous studies and indicates low frequency band of electromagnetic fields [EMF] [200 microT intensity] in cell phone may not have any effect on the learning acquisition and spatial memory in rat
ABSTRACT
Nowadays radiosensitive polymer gels are used as a reliable dosimetry tool for verification of 3D dose distributions. Special characteristics of these dosimeters have made them useful for verification of complex dose distributions in clinical situations. The aim of this work was to evaluate the capability of a normoxic polymer gel to determine electron dose distributions in different slab phantoms in presence of small heterogeneities. Different cylindrical phantoms consisting gel were used under slab phantoms during each irradiation. MR images of irradiated gel phantoms were obtained to determine their R2 relaxation maps. 1D and 2D lateral dose profiles were acquired at depths of 1 cm for an 8 MeV beam and 1 and 4 cm for the 15 MeV energy, and then compared with the lateral dose profiles measured using a diode detector. In addition, 3D dose distributions around these heterogeneities for the same energies and depths were measured using a gel dosimeter. Dose resolution for MR gel images at the range of 0-10 Gy was less than 1.55 Gy. Mean dose difference and distance to agreement [DTA] for dose profiles were 2.6% and 2.2 mm, respectively. The results of the MAGIC-type polymer gel for bone heterogeneity at 8 MeV showed a reduction in dose of approximately 50% and 30% and 10% at depths 1 and 4 cm at 15 Mev. However, for air heterogeneity increases in dose of approximately 50% at depth 1 cm under the heterogeneity at 8 MeV and 20% and 45% respectively at 15 MeV. However, for air heterogeneity increae in dose of approximately 50% at depth 1 cm under the heterogeneity at 8 MeV and 20% and 45% respectively at 15 MeV were observed. Generally, electron beam distributions are significantly altered in the presence of tissue inhomogeneities such as bone and air cavities, this being related to mass stopping and mass scattering powers of heterogeneous materials. A the same time, hot and cold scatter lobes under heterogeneity regions due to scatter edge effects were also seen. However, these effects [increased dose, reduced dose, hot and cold spots] at deeper depths, are compensated with the contributions of scattered electrons. Our study showed that normoxic polymer gels are reliable detectors for determination of electron dose distributions due to their characteristics such as tissue equivalence, energy independence, and 2D and 3D dose visualization capabilities
Subject(s)
Gels , Ascorbic Acid , Gelatin , Hydroquinones , Methacrylates , Polymers , Copper Sulfate , Electrons , Radiation Dosage , Magnetic Resonance ImagingABSTRACT
The efficacious effects of pulsed electromagnetic field [PEMF] under the certain field parameters like frequency and the field intensity have been reported for various tissue and molecules. Since collagen is found abundantly in most tissue structures, this research was designed to further investigate the effects of extremely low frequency [ELF] PEMF on the synthesis of the epidermal collagen. To do the task, six groups of animals each consisting of eight mature male rats were selected randomly as one group for the control and five for the test. The field was generated by using a parallel set of Helmholtz coil. The first set of experiments was carried out at the peak intensity of 2 mT [milli Tesla] for different frequencies of 25, 50 and 100 Hz. Since the most effective frequency turned out to be 25 Hz, another set of experiment was conducted using this frequency and two different field intensities of 1 and 4 mT. The field was applied for 2.5 h/day lasting for 8 days, keeping the same procedure for the control group except for the field turned off. On the ninth day, the rats were sacrificed and the skin samples from the dorsal region were taken for biochemical assessment of collagen by measuring hydroxyproline content using Stegeman-Stalder method and histological assessment. The data indicated that pulsed electromagnetic field of 2 mT at 25 Hz increased the collagen synthesis [P<0.05]. The other intensities and frequency setting did not have much distinguishable effect, however, at the frequency of 25 Hz and 4 mT, the field effect on the collagen increase was also noticeable. It was concluded that applying the field parameters of 25 Hz and 2 mT peak intensity for 2.5 h/day during eight days rendered a significant increase in collagen synthesis in rat skin. Histological observations were consistent with the biochemical findings