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Pulsed Electromagnetic Fields (pulsed + electromagnetic_field)
Selected AbstractsPulsed electromagnetic fields enhance BMP-2 dependent osteoblastic differentiation of human mesenchymal stem cellsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 9 2008Z. Schwartz Abstract Mesenchymal stem cells (MSCs) express an osteoblastic phenotype when treated with BMP-2, and BMP-2 is used clinically to induce bone formation although high doses are required. Pulsed electromagnetic fields (PEMF) also promote osteogenesis in vivo, in part through direct action on osteoblasts. We tested the hypothesis that PEMF enhances osteogenesis of MSCs in the presence of an inductive stimulus like BMP-2. Confluent cultures of human MSCs were grown on calcium phosphate disks and were treated with osteogenic media (OM), OM containing 40 ng/mL rhBMP-2, OM,+,PEMF (8 h/day), or OM,+,BMP-2,+,PEMF. MSCs demonstrated minor increases in alkaline phosphatase (ALP) during 24 days in culture and no change in osteocalcin. OM increased ALP and osteocalcin by day 6, but PEMF had no additional effect at any time. BMP-2 was stimulatory over OM, and PEMF,+,BMP-2 synergistically increased ALP and osteocalcin. PEMF also enhanced the effects of BMP-2 on PGE2, latent and active TGF-,1, and osteoprotegerin. Effects of PEMF on BMP-2,treated cells were greatest at days 12 to 20. These results demonstrate that PEMF enhances osteogenic effects of BMP-2 on MSCs cultured on calcium phosphate substrates, suggesting that PEMF will improve MSC response to BMP-2 in vivo in a bone environment. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1250,1255, 2008 [source] Effects of weak static magnetic fields on endothelial cellsBIOELECTROMAGNETICS, Issue 4 2010Carlos F. Martino Abstract Pulsed electromagnetic fields (PEMFs) have been used extensively in bone fracture repairs and wound healing. It is accepted that the induced electric field is the dose metric. The mechanisms of interaction between weak magnetic fields and biological systems present more ambiguity than that of PEMFs since weak electric currents induced by PEMFs are believed to mediate the healing process, which are absent in magnetic fields. The present study examines the response of human umbilical vein endothelial cells to weak static magnetic fields. We investigated proliferation, viability, and the expression of functional parameters such as eNOS, NO, and also gene expression of VEGF under the influence of different doses of weak magnetic fields. Applications of weak magnetic fields in tissue engineering are also discussed. Static magnetic fields may open new venues of research in the field of vascular therapies by promoting endothelial cell growth and by enhancing the healing response of the endothelium. Bioelectromagnetics 31:296,301, 2010. © 2010 Wiley-Liss, Inc. [source] Pulsed electromagnetic fields accelerate wound healing in the skin of diabetic ratsBIOELECTROMAGNETICS, Issue 4 2010Iran Goudarzi Abstract Delayed wound healing is a common complication in diabetes mellitus. From this point of view, the main purpose of the present study is to investigate the effect of extremely low frequency pulsed electromagnetic fields (ELF PEMFs) on skin wound healing in diabetic rats. In this study, diabetes was induced in male Wistar rats via a single subcutaneous injection of 65,mg/kg streptozocin (freshly dissolved in sterile saline, 0.9%). One month after the induction of diabetes, a full-thickness dermal incision (35,mm length) was made on the right side of the paravertebral region. The wound was exposed to ELF PEMF (20,Hz, 4,ms, 8,mT) for 1,h per day. Wound healing was evaluated by measuring surface area, percentage of healing, duration of healing, and wound tensile strength. Obtained results showed that the duration of wound healing in diabetic rats in comparison with the control group was significantly increased. In contrast, the rate of healing in diabetic rats receiving PEMF was significantly greater than in the diabetic control group. The wound tensile strength also was significantly greater than the control animals. In addition, the duration of wound healing in the control group receiving PEMF was less than the sham group. Based on the above-mentioned results we concluded that this study provides some evidence to support the use of ELF PEMFs to accelerate diabetic wound healing. Further research is needed to determine the PEMF mechanisms in acceleration of wound healing in diabetic rats. Bioelectromagnetics 31:318,323, 2010. © 2010 Wiley-Liss, Inc. [source] Pulsed electromagnetic fields stimulation affects BMD and local factor production of rats with disuse osteoporosisBIOELECTROMAGNETICS, Issue 2 2010Wei-Wei Shen Abstract Pulsed electromagnetic fields (PEMF) have been used widely to treat nonunion fractures and related problems in bone healing, as a biological and physical method. With the use of Helmholtz coils and PEMF stimulators to generate uniform time-varying electromagnetic fields, the effects of extremely low frequency electromagnetic fields on bone mineral density (BMD) and local factor production in disuse osteoporosis (DOP) rats were investigated. Eighty 4-month-old female Sprague Dawley (SD) rats were randomly divided into intact (INT) group, DOP group, calcitonin-treated (CT) group, and PEMF stimulation group. The right hindlimbs of all the rats were immobilized by tibia-tail fixation except for those rats in the INT group. Rats in the CT group were injected with calcitonin (2,IU/kg, i.p., once a day) and rats in the PEMF group were irradiated with PEMF immediately postoperative. The BMD, serum transforming growth factor-beta 1 (TGF-,1), and interleukin-6 (IL-6) concentration of the proximal femur were measured 1, 2, 4, and 8 weeks after treatment. Compared with the CT and DOP groups, the BMD and serum TGF-,1 concentration in the PEMF group increased significantly after 8 weeks. The IL-6 concentration in the DOP group was elevated significantly after operation. The PEMF group showed significantly lower IL-6 level than the DOP group. The results found demonstrate that PEMF stimulation can efficiently suppress bone mass loss. We, therefore, conclude that PEMF may affect bone remodeling process through promoting TGF-,1 secretion and inhibiting IL-6 expression. Bioelectromagnetics 31:113,119, 2010. © 2009 Wiley-Liss, Inc. [source] Pulsed electromagnetic fields affect osteoblast proliferation and differentiation in bone tissue engineeringBIOELECTROMAGNETICS, Issue 7 2007Ming-Tzu Tsai Abstract Bone tissue engineering is an interdisciplinary field involving both engineers and cell biologists, whose main purpose is to repair bone anatomical defects and maintain its functions. A novel system that integrates pulsed electromagnetic fields (PEMFs) and bioreactors was applied to bone tissue engineering for regulating osteoblast proliferation and differentiation in'vitro. Osteoblasts were acquired from the calvaria of newborn Wistar rats and isolated after sequential digestion. Poly(DL -lactic-co-glycolic acid) (PLGA) scaffolds were made by the solvent merging/particulate leaching method. Osteoblasts were seeded into porous PLGA scaffolds with 85% porosity and cultured in bioreactors for the 18-day culture period. Cells were exposed to PEMF pulsed stimulation with average (rms) amplitudes of either 0.13, 0.24, or 0.32 mT amplitude. The resulting induced electric field waveform consisted of single, narrow 300 µs quasi-rectangular pulses with a repetition rate of 7.5'Hz. The results showed that PEMF stimulation for 2 and 8 h at .13 mT increased the cell number on days 6 and 12, followed by a decrease on day 18 using 8 h stimulation. However, ALP activity was decreased and then increased on days 12 and 18, respectively. On the other hand, PEMF-treated groups (irrespective of the stimulation time) at 0.32 mT inhibited cell proliferation but enhanced ALP activity during the culture period. These findings suggested that PEMF stimulation with specific parameters had an effect on regulating the osteoblast proliferation and differentiation. This novel integrated system may have potential in bone tissue engineering. Bioelectromagnetics 28:519,528, 2007. © 2007 Wiley-Liss, Inc. [source] Pulsed electromagnetic fields induce peripheral nerve regeneration and endplate enzymatic changesBIOELECTROMAGNETICS, Issue 1 2005J.A. De Pedro Abstract An experimental study was carried out in rats with the purpose of demonstrating the capacity of pulsed electromagnetic fields (PEMFs) to stimulate regeneration of the peripheral nervous system (PNS). Wistar and Brown Norway (BN) rats were used. Direct sciatic nerve anastomoses were performed after section or allograft interposition. Treatment groups then received 4 weeks of PEMFs. Control groups received no stimulation. The evaluation of the results was carried out by quantitative morphometric analysis, demonstrating a statistically significant increase in regeneration indices (P,<,0.05) in the stimulated groups (9000,±,5000 and 4000,±,6000) compared to the non-stimulated groups (2000,±,4000 and 700,±,200). An increase of NAD specific isocitrate dehydrogenase (IDH) activity was found along with an increase in the activity of acetyl cholinesterase at the motor plate. The present study might lead to the search for new alternatives in the stimulation of axonal regenerative processes in the PNS and other possible clinical applications. Bioelectromagnetics 26:20,27, 2005. © 2004 Wiley-Liss, Inc. [source] Effect of short duration electromagnetic field exposures on rat massBIOELECTROMAGNETICS, Issue 1 2002Michelle A. Sandrey Abstract Daily preexposure and postexposure mass measurements of 65 rats (young males and females, old males) a proprietary pulsed wound healing field, pulsed electromagnetic field, (PEMF), or their control fields for 4 h/day for 21 days. Statistical analysis of mass changes over time showed that young rats exposed to PEMF lost more mass and recovered it more slowly compared to controls (2,4% more loss) than did older PEMF exposed rats or any 60 Hz exposed rats. We conclude that daily preexposure and postexposure mass measurements are needed to adequately assess the effects of electromagnetic fields on body mass. Bioelectromagnetics 23:2,6, 2002. © 2002 Wiley-Liss, Inc. [source] Effect of pulsed electromagnetic fields on maturation of regenerate bone in a rabbit limb lengthening model,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2006Kenneth F. Taylor Abstract To study the effect of applying pulsed electromagnetic fields (PEMF) during the consolidation phase of limb lengthening, a mid-tibial osteotomy was performed in 18 adult New Zealand White rabbits and an external fixator was applied anteromedially. Animals were randomly assigned to treatment and control groups. After a 7-day latency period, the tibiae were distracted 0.5 mm every 12 h for 10 days. The treatment group received a 20-day course of PEMF for 60 min daily, coinciding with initiation of the consolidation phase. The control group received sham PEMF. Radiographs were performed weekly after distraction. Animals were euthanized 3 weeks after the end of distraction. Radiographic analysis revealed no significant difference in regenerate callus area between treatment and control tibiae immediately after distraction, at 1 week, 2 weeks, or 3 weeks after distraction (,p,=,0.71, 0.22, 0.44, and 0.50, respectively). There was also no significant difference in percent callus mineralization (,p,=,0.96, 0.69, 0.99, and 0.99, respectively). There was no significant difference between groups with respect to structural stiffness (,p,=,0.80) or maximal torque to failure (,p,=,0.62). However, there was a significant positive difference in mineral apposition rate between groups during the interval 1,2 weeks post-distraction (,p,<,0.05). This difference was no longer evident by the interval 2,3 weeks post-distraction. While PEMF applied during the consolidation phase of limb lengthening did not appear to have a positive effect on bone regenerate, it increased osteoblastic activity in the cortical bone adjacent to the distraction site. Since the same PEMF signal was reported to be beneficial in the rabbit distraction osteogenesis when applied during distraction phase and consolidation phase, application of PEMF in the early phase may be more effective. Further work is necessary to determine optimal timing of the PEMF stimulation during distraction osteogenesis. © 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Pulsed electromagnetic fields affect osteoblast proliferation and differentiation in bone tissue engineeringBIOELECTROMAGNETICS, Issue 7 2007Ming-Tzu Tsai Abstract Bone tissue engineering is an interdisciplinary field involving both engineers and cell biologists, whose main purpose is to repair bone anatomical defects and maintain its functions. A novel system that integrates pulsed electromagnetic fields (PEMFs) and bioreactors was applied to bone tissue engineering for regulating osteoblast proliferation and differentiation in'vitro. Osteoblasts were acquired from the calvaria of newborn Wistar rats and isolated after sequential digestion. Poly(DL -lactic-co-glycolic acid) (PLGA) scaffolds were made by the solvent merging/particulate leaching method. Osteoblasts were seeded into porous PLGA scaffolds with 85% porosity and cultured in bioreactors for the 18-day culture period. Cells were exposed to PEMF pulsed stimulation with average (rms) amplitudes of either 0.13, 0.24, or 0.32 mT amplitude. The resulting induced electric field waveform consisted of single, narrow 300 µs quasi-rectangular pulses with a repetition rate of 7.5'Hz. The results showed that PEMF stimulation for 2 and 8 h at .13 mT increased the cell number on days 6 and 12, followed by a decrease on day 18 using 8 h stimulation. However, ALP activity was decreased and then increased on days 12 and 18, respectively. On the other hand, PEMF-treated groups (irrespective of the stimulation time) at 0.32 mT inhibited cell proliferation but enhanced ALP activity during the culture period. These findings suggested that PEMF stimulation with specific parameters had an effect on regulating the osteoblast proliferation and differentiation. This novel integrated system may have potential in bone tissue engineering. Bioelectromagnetics 28:519,528, 2007. © 2007 Wiley-Liss, Inc. [source] Pulsed electromagnetic fields induce peripheral nerve regeneration and endplate enzymatic changesBIOELECTROMAGNETICS, Issue 1 2005J.A. De Pedro Abstract An experimental study was carried out in rats with the purpose of demonstrating the capacity of pulsed electromagnetic fields (PEMFs) to stimulate regeneration of the peripheral nervous system (PNS). Wistar and Brown Norway (BN) rats were used. Direct sciatic nerve anastomoses were performed after section or allograft interposition. Treatment groups then received 4 weeks of PEMFs. Control groups received no stimulation. The evaluation of the results was carried out by quantitative morphometric analysis, demonstrating a statistically significant increase in regeneration indices (P,<,0.05) in the stimulated groups (9000,±,5000 and 4000,±,6000) compared to the non-stimulated groups (2000,±,4000 and 700,±,200). An increase of NAD specific isocitrate dehydrogenase (IDH) activity was found along with an increase in the activity of acetyl cholinesterase at the motor plate. The present study might lead to the search for new alternatives in the stimulation of axonal regenerative processes in the PNS and other possible clinical applications. Bioelectromagnetics 26:20,27, 2005. © 2004 Wiley-Liss, Inc. [source] | ||||||||||