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The study aims to explore the effect of mesenchymal stem cells-derived exosomes (MSCs-Exo) on staurosporine (STS)-induced chondrocyte apoptosis before and after exposure to pulsed electromagnetic field (PEMF) at different frequencies. The AMSCs were extracted from the epididymal fat of healthy rats before and after exposure to the PEMF at 1 mT amplitude and a frequency of 15, 45, and 75 Hz, respectively, in an incubator. MSCs-Exo was extracted and identified. Exosomes were labeled with DiO fluorescent dye, and then co-cultured with STS-induced chondrocytes for 24 h. Cellular uptake of MSC-Exo, apoptosis, and the protein and mRNA expression of aggrecan, caspase-3 and collagenⅡA in chondrocytes were observed. The study demonstrated that the exposure of 75 Hz PEMF was superior to 15 and 45 Hz PEMF in enhancing the effect of exosomes in alleviating chondrocyte apoptosis and promoting cell matrix synthesis. This study lays a foundation for the regulatory mechanism of PEMF stimulation on MSCs-Exo in inhibiting chondrocyte apoptosis, and opens up a new direction for the prevention and treatment of osteoarthritis.
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Animals , Rats , Apoptosis , Chondrocytes , Electromagnetic Fields , Exosomes/physiology , Mesenchymal Stem Cells/metabolismABSTRACT
Objective:To observe any regulatory effect of a pulsed electromagnetic field (PEMF) on A2A adenosine receptors (A2ARs) in the nucleus pulposus of rats with intervertebral disc degeneration (IDD), and to explore any combination with the A2ARs′ agonist-mediating ROS/PI3K/Akt signaling pathway.Methods:Fifty Sprague-Dawley rats were randomly divided into a control group, an intervertebral disc degeneration group (the model group), an A2AR agonist CGS-21680 treatment group (the agonist group), a PEMF group and a PEMF combined with CGS-21680 treatment group (the observation group). IDD was modeled in all except the rats in the control group. 100μL of CGS-21680 (100μg/kg) was injected into the L 5-6 intervertebral discs of the agonist group, while the PEMF group was given 30 minutes of PEMF intervention daily for 14 days at 1.5mT and 75Hz with a pulse width of 150μs. The observation group was injected with CGS-21680 and then given the same PEMF intervention. Primary nucleus pulposus cells from each group (50ng/mL) were cultured and the expressions of 8-OHDG, SOD, MDA and ROS were detected by immunohistochemistry, immunofluorescence or with an ELISA kit. The A2AR, PI3K, AKT and p-AKT protein levels were detected using western blotting. Results:The nucleus pulposus cells and the annulus fibrosus were obviously wrinkled, necrotic and broken in the model group but the annulus fibrosus was intact and the nucleus pulposus was almost normal in the observation group. Compared with the model group, the levels of SOD and A2AR, PI3K, p-AKT and AKT protein were higher in the agonist, PEMF and observation groups, while the expressions of MDA, ROS and 8-OHDG were weaker. The ROS level in the observation group was significantly lower than that in the agonist and PEMF groups, and the phosphorylation level of p-AKT in the observation group was significantly higher than in the agonist and PEMF groups. The average levels of SOD, A2AR, PI3K, p-AKT and AKT protein in the nucleus pulposus cells of the agonist, PEMF and observation groups were significantly higher than the IL-1β group′s average, while the average levels of MDA, ROS and 8-OHDG were significantly lower. The ROS levels in the observation group were significantly lower than in the agonist and PEMF groups, while the A2AR protein content and p-AKT phosphorylation in the observation group were significantly greater. The average Bax levels in the nucleus pulposus cells of the agonist, PEMF and observation groups were significantly lower than that in the IL-1β group, and the expression of Bcl-2 was significantly increased. There was significantly less apoptosis observed in the observation group than in the agonist and PEMF groups, while the expression of Bcl-2 was significantly higher.Conclusions:PEMF plays an anti-oxidative stress role by up-regulating A2AR activity and reducing ROS generation. Treatment with PEMF and A2AR agonist could further activate the phosphorylation of PI3K/Akt, down-regulate Bax and up-regulate Bcl-2, thus inhibiting the apoptosis of nucleus pulposus cells and alleviating the malignant progression of IDD.
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Objective To investigate whether the low-frequency pulsed electromagnetic fields (LF-PEMFs) can enhance the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) induced by bone morphogenetic protein 9 (BMP9). Methods We isolated CD146＋/STRO-1＋ cells (namely PDLSC) from periodontal ligament cells of healthy human premolars, transfected the PDLSC with BMP9-overexpressing recombinant adenoviruses (Ad-GFP-BMP9), exposed the cells to the different intensities of PEMF stimulation (15 Hz, 0.6，1.2，1.8，2.4，3.0 mT, 1 h/12 h), and then detected the expression of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN) by qRT-PCR and Western blotting. Results Overexpression of BMP9 significantly promoted the expression of osteogenic markers (Runx2, ALP, OCN and OPN) in PDLSC (P0.05). After the intervention with 1.2, 1.8, 2.4 and 3.0 mT PEMF, the expression levels of osteogenic markers in PDLSC were significantly higher than those exposed to BMP9 alone (P0.05), and reached the peak at 2.4 mT (P0.05), indicating that LF-PEMFs enhanced BMP9-induced osteogenic differentiation of PDLSC, and there was a “window effect”. Conclusion LF-PEMFs stimulation (15 Hz, 1.8 to 3.0 mT) can enhance BMP9-induced osteogenesis of hPDLSCs in vitro.
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Objective@#To explore the expression of the A2A adenosine receptor and the inflammatory cytokines interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) in human degenerative nucleus pulposus (NP) cells after they have been treated with a pulsed electromagnetic field (PEMF).@*Methods@#Human degenerative NP cells were cultured in vitro and treated using an 0.8mT PEMF with a pulse frequency of 50Hz. The pulse width was 150μs and the exposure time was 30min, repeated 5 times at 12 hour intervals. The expression of the A2A adenosine receptor in NP cells was determined using western blotting and reverse transcription polymerase chain reactions. The expression of the inflammatory cytokines IL-1β and TNF-α were detected using enzyme-linked immunosorbent assays (ELISA). The human degenerative NP cells were also treated with an antagonist and agonist of the A2A adenosine receptor, and the expression of IL-1β and TNF-α were also determined using ELISA.@*Results@#After the PEMF treatment the expression of the A2A adenosine receptor increased significantly, while the expression of IL-1β and TNF-α decreased significantly. However, the A2A adenosine receptor antagonist reversed the inhibitory effect of the PEMF on the expression of IL-1β and TNF-α, while the agonist played an opposite role.@*Conclusion@#A PEMF can significantly inhibit the expression of IL-1β and TNF-α in human degenerative NP cells, which could be related to up-regulation of the expression of the A2A adenosine receptor in those cells.
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Objective To investigate the effect of a pulsed electromagnetic field ( PEMFS) on bone mineral density and bone metabolism in males with osteoporosis after a stroke. Methods Fifty male stroke survivors with os-teoporosis were randomly divided into a control group and a treatment group, both of 25. Both groups were treated with routine rehabilitation, oral calcium carbonate and vitamin D3 tablets, while the treatment group was additionally pro-vided with PEMFS treatment. The subjects′bone mineral density ( BMD) and their blood levels of bone-specific alka-line phosphatase (B-ALP), type I procollagen amino-terminal peptide (PINP) and type β-I collagen cross-linked carboxy-terminal peptide (β-CTx) were measured before and after the 12 weeks of treatment. Results After the treatment the BMD values of the lumbar spine, femoral neck, trochanter and Ward′s triangle had increased signifi-cantly in both groups, but the average BMD values of the lumbar spine and femoral neck in the treatment group were significantly higher than those of the control group. After the treatment, the average B-ALP, PINP andβ-CTx levels of both groups had also improved significantly compared with before the treatment, but the average improvement in all three among the treatment group was significantly greater than among the controls. Conclusion PEMFS treatment supplementing routine rehabilitation, oral calcium carbonate and vitamin D3 tablets can improve bone formation, re-duce bone resorption and increase bone mineral density in men after a stroke.
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Objective To observe the effect of a pulsed electromagnetic field (PEMF) on the bone structure and metabolism of rats with disuse osteoporosis (DOP).Methods One hundred 4-month-old female Sprague-Dawley rats were randomly divided into a control group (INT group),an osteoporosis model group (DOP group),a sodium alendronate group (ALN group) and a pulsed electromagnetic field group (PEMF group),each of 25.The right hind-limbs of the rats in the DOP,ALN and PEMF groups were immobilized by tibia-tail fixation for two weeks to establish a DOP model.The rats in the ALN group were given 1 mg/kg of sodium alendronate once a day,while those in the PEMF group received PEMF at 3.82 mT and 10 Hz with a pulse time of 8 ms for 40 min/d.Five rats in each group were sacrificed at the 2nd,4th,8th and 12th week and their right hind-limbs were separated to measure the bone mineral density (BMD),structural mechanics indexes (the maximum load,maximum displacement and rupture energy) and material mechanics indexes (maximum stress,maximum strain and modulus).Moreover,the expression of tumor necrosis factor alpha (TNF-α) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemical methods.Results The average BMD of the model group was significantly lower than that of the ALN group after 2 weeks,and lower than that of the PEMF group after 4 and 8 weeks.After 12 weeks the average BMD of the PEMF group was significantly higher than that of the ALN and model groups.After two and four weeks,all the structural and material mechanics measurements had decreased significantly compared with those of the control group.The average maximum displacement and load of the ALN group had increased significantly compared with the model group after 4 weeks of treatment.After 8 weeks the average maximum load,maximum displacement,rupture energy and maximum stress of the ALN and PEMF groups had increased significantly compared with the model group.Compared with the model group,the average level of TNF-α decreased gradually in both the ALN and PEMF groups from the 2nd week on,while that of BMP-2 increased from the same time point.However,at the 8th week the expression of BMP-2 protein in the PEMF group was on average significantly higher than in the ALN group.Conclusion Both PEMF and sodium alendronate can increase bone density,but PEMF has more persistent effects.
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Objective To observe the influence of a pulsating electromagnetic field (PEMF) on the expression of runt-related transcription factor 2 (Runx2) in ovariectomized rats so as to explore the possibility of using PEMFs to treat osteoporosis.Methods Sixty female Sprague-Dawley rats were randomly divided into four groups of 15-a control group (Sham group),an ovary resection group (OVX group),a resection group treated with alendronate sodium (OVX+ALN group) and a resection group exposed to a PEMF (PEMFs group).Both ovaries were resected to induce osteoporosis,except in the sham group where the adipose tissues around the ovaries were cut bilaterally without resection.After the operation,the ALN group were given 2 mg/kg of alendronate by gavage daily for 30 days,while the PEMFs group was exposed to a 3.8 mT electromagnetic field pulsing at 8 Hz for 40 min twice daily for 30 days.There was no intervention in the other two groups.The animals were sacrificed using intra-peritoneal injection of sodium pentobarbital and the density of their femurs was measured.The expression of Runx2 protein and Runx2 mRNA were detected using western blotting and quantitative PCR.Results The average bone density,Runx2 protein level and Runx2 mRNA level of the PEMFs group were all significantly higher than those of the OVX group,but there was no significant difference between the PEMFs group and ALN group averages.Conclusion PEMF exposure can upregulate the expression of Runx2 protein and Runx2 mRNA in female rats after ovary resection.This may be one of the mechanisms by which PEMFs treat osteoporosis.
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Objective To observe the influence of a pulsating electromagnetic field (PEMF) on the expression of runt-related transcription factor 2 (Runx2) in ovariectomized rats so as to explore the possibility of using PEMFs to treat osteoporosis.Methods Sixty female Sprague-Dawley rats were randomly divided into four groups of 15-a control group (Sham group),an ovary resection group (OVX group),a resection group treated with alendronate sodium (OVX+ALN group) and a resection group exposed to a PEMF (PEMFs group).Both ovaries were resected to induce osteoporosis,except in the sham group where the adipose tissues around the ovaries were cut bilaterally without resection.After the operation,the ALN group were given 2 mg/kg of alendronate by gavage daily for 30 days,while the PEMFs group was exposed to a 3.8 mT electromagnetic field pulsing at 8 Hz for 40 min twice daily for 30 days.There was no intervention in the other two groups.The animals were sacrificed using intra-peritoneal injection of sodium pentobarbital and the density of their femurs was measured.The expression of Runx2 protein and Runx2 mRNA were detected using western blotting and quantitative PCR.Results The average bone density,Runx2 protein level and Runx2 mRNA level of the PEMFs group were all significantly higher than those of the OVX group,but there was no significant difference between the PEMFs group and ALN group averages.Conclusion PEMF exposure can upregulate the expression of Runx2 protein and Runx2 mRNA in female rats after ovary resection.This may be one of the mechanisms by which PEMFs treat osteoporosis.
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Objective: To explore the clinical research on the treatment of osteoporosis with calcitonin and Low frequency pulse electromagnetic field. Methods:Selected 84 cases of primary osteoporosis were randomly divided into control group and treatment group, 42 cases in each group, two groups were given calcium, vitamin D and other drugs conventional treatment, on the basis of the control group, intramuscular injections salmon calcitonin in the treatment group and intramuscular injection of salmon calcitonin with PEMF therapy, before treatment and after 3 and 6 months, respectively. Results: Two groups of patients after treatment, the pain was significantly reduced compared with before treatment, the longer the treatment, the more obvious decline;Treatment of three months, six months later, the treatment group compared with the control group bone mineral density were significant differences(t=3.129, t=6.457;P<0.05);The two groups no serious adverse reactions. Conclusion:Osteoporosis patients in the conventional therapy treatment based on intramuscular injection of salmon calcitonin and with PEMF treatment can significantly reduce the patient's pain, increase bone density, efficacy, adverse reactions, with some clinical reference significance.
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Objective To investigate the effects of pulsed electromagnetic fields (PEMF) on homing and proliferation-related genes of mouse osteoblasts.Methods 9 week-old C57BL/6 mice were treated with PEMF (70 Hz,1 mT) for 4～5 weeks,while mice in control group didn't not receive PEMF.Bone marrow cells of femurs and tibias were flushed out,and the bones were minced and incubated at 37 ℃ with a type Ⅰ collagenase.Bone associated mononuclear cells (MNCs) were isolated via density centrifugation with Lymphoprep.Magnetic cell sorting was used before flow-cytometric sorting,and the ALCAM+Sca-1-cells were collected.The homing and proliferation-related genes expressed in ALCAM+Sca-1-cells were detected with high throughput microarray and RT-PCR.Results The expression of Jag1 and Ang-1 in mouse osteoblasts increased under the effects of PEMF.Conclusions PEMF may have regulation effects on HSC (hematopoietic stem cell) survival through modulating the homing and proliferationrelated genes in ALCAM+Sca-1-osteoblasts.
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Objective To observe any therapeutic effect of pulsed electromagnetic fields (PEMFs) on bone loss in spinal cord injury (SCI) patients.Methods Fifty-five patients with SCI were divided into two groups randomly.The twenty-six patients in the control group (group B) were given only routine rehabilitation treatment; the twenty-six patients in the treatment group (group A) received PEMF therapy in addition.Results After 12 weeks of treatment,the average bone mineral density (BMD) of the proximal femur (including total,neck,Wards,inter,troch) in group A was significantly higher than in group B.The levels of bone-gamma-carboxyglutamic acid containing protein (BGP) and 1,25 (OH)2D3 in group A increased significantly,while they decreased in group B.Urine-pyridinium/crealinine (U-Pyd/Cr) levels in group A decreased significantly,while in group B they were higher than before.There were statistically significant differences between the two groups.Conclusion PEMF treatment can effectively retard bone loss in SCI patients.It has good preventive and curative effects on osteoporosis after SCI.
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Objective To observe any effects of pulsed electromagnetic fields (PEMFs) on the expression of transforming growth factor beta-1 (TGF-β1) after sciatic nerve injury and to investigate the possible mechanism of any regeneration of the injured sciatic nerve.MethodsForty-eight SD rats were randomly divided into a PEMF treatment group,a model group and a normal control group with 16 rats in each group.The three groups were then sub-divided into 1 day,3 day,7 day and 14 day subgroups.The rats of the model and treatment groups were clamped to produce a sciatic nerve injury model.The treatment sub groups were exposed to a 9 mT PEMF at 14 Hz for 2 hours once daily for 1,3,7 and 14 days,respectively.The model group was given sham exposure and the normal control group was reared conventionally and not given any special treatment.The histological changes in the rats' sciatic nerves were observed under a light microscope after hematoxylin-eosin staining.Expression of TGF-β1 was detected by immunohistochemical methods.ResultsAfter 7 and 14 days of treatment,Wallerian degeneration of the sciatic nerve in the treatment group was more obvious than in the model group.The expression of TGF-β1 increased during the treatment process and reached a maximum at the 14th day after nerve injury.The expression of TGF-β1 had increased significantly in the model and treatment groups compared with the control group at all observation time points.At the 3rd,7th and 14th day after the operation,the expression of TGF-β1 in the treatment group was significantly higher than that in the model group. Conclusion PEMFs can accelerate Wallerian degeneration of peripheral nerves and can up-regulate the expression of TGF-β1 after sciatic nerve injury,at least in rats.
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Objective To investigate the effects of a pulsed electromagnetic field (PEMF) on cell proliferation,differentiation and the genetic expression of osteogenesis specific transcription factor-Osterix (OSX) in the calvaria-derived osteoblasts of SD rats.MethodsPrimary osteoblasts were separated from the calvarias of Sprague-Dawley rats 24 hours after birth by trypsinazation and collagenase digestion.The osteoblasts at passage 4 were randomly divided into a control group and a PEMF group,Cells in the PEMF group were placed onto PEMF therapeutic apparatus and exposed to 11 mT radiation at 12 Hz for 1 h per day for 3 days.The osteoblasts' proliferation ability was then detected via methylthiazdyl tetrazolium assay.Alkaline phosphatase (ALP) activity in the cell lysate and the supernatant fluid was assayed through disodium phenyl phosphate colorimetric determination to determine the cells'differentiation ability.OSX mRNA expression was determined using real time reverse transcription polymerase chain reaction (RT-PCR).ResultsThe proliferation of osteoblasts in the PEMF group was significantly greater than in the control group.PEMF exposure suppressed ALP activity in both the lysate and the supernatant of the osteoblasts.The OSX mRNA expression in the PEMF group was significantly down-regulated compared with the control group.ConclusionPEMF at 12 Hz and 11 mT can promote the proliferation of osteoblasts,but it inhibits cellular differentiation and down-regulates the mRNA expression of OSX.
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Objective To study the in vitro and in vivo effects of pulsed electromagnetic fields (PEMFs) on osteoclast and osteoblast precursor cells.MethodsTo observe the in vitro effect of PEMFs,femur bone marrow cells of 8 week old female SD rats were collected.According to different treating doses,rats were divided into four treatment groups and one control group.After the treatment,the clones of granuloeyte/maerophage colony forming unit(CFU-GM) and fibroblast colony forming units(CFU-F) were measured respectively.To observe the combined in vitro and in vivo effect of PEMFs,8 week old female SD rats were randomly divided into three groups: 2-70 group,ovariectomization (OVX) group and SHAM group.Rats in the 2-70 group and OVX group were bilateral ovariectomized,while rats in the SHAM group were sham-ovariectomized.12 weeks after ovariectomization,the 2-70 group was exposed to PEMFs while the other groups were left untreated.Then,femur bone marrow cells of the rats were collected.According to the way whether the groups were treated with PEMFs,the cells were divided into six groups: 2-70 with/without treatment,OVX with/without treatment,SHAM with/without treatment.After the treatments,the clones of CFU-GM and CFU-F were measured respectively.Resultsin vitro effect of PEMFs: Compared with the control group,the CFU-GMin the treated groups reduced while the CFU-F increased.PEMFs effect in vitro and in vivo: The CFU-F in treated groupsincreased,whileno.significantdifferencesofCFU-GMwerefoundamongthegroups.Conclusion PEMFs has inhibitory effect on osteoelast precursor cells and enhances the proliferation of osteoblast precursor cells when simply applied in vitro.When PEMFs was applied in combined manner of in vitro and in vivo,it shows that PEMFs enhance the proliferation of osteoblast precursor cells but has no inhibitory effects on osteoelast precursor cells.
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Objective To observe the effects of low-frequency pulsed electromagnetic fields (LFPEMFs) on microcirculation angiogenesis in the hindlimbs of diabetic rats with acute ischemia. Methods Models of acute hindlimb ischemia were established in 60 male Sprague-Dawley diabetic rats. The diabetes model was established using 60 mg/kg intraperitoneal injections of streptozotocin (STZ). Fasting blood glucose levels were greater than 300 mg/dL. The rats were randomly divided into experimental and control groups. The rats in the experimental group were exposed to low-frequency pulsed electromagnetic fields for 2 hours each day, while the control group was not given any treatment. Laser-Doppler perfusion was used to measure blood flow in the ischemic hindlimb on days 0,7, 14 and 28 after the operation. The immunofluorescence of rat endothelial cell antigen-1 ( RECA-1) was used to evaluate the changes in angiogenesis. The levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) were determined by both Western blotting and ELISA, and VEGFR2 and FGFR1 levels in the ischemic skeletal muscle were determined by Western blotting on days 7, 14 and 28 after the operation. Results The average perfusion ratio was significantly greater in the experimental group at days 14 and 28 compared with the control group. RECA-1 density in the tissues had increased significantly in the experimental group at the 14th and 28th day. The same was observed for FGF-2 and its receptor, but there was no significant difference for VEGF or its receptor in either group. Conclusions LFPMEFs can promote angiogenesis in acute hindlimb ischemia of diabetic rats by up-regulating FGF-2. This suggests that LFPMEFs may be useful for preventing and treating lower limb ischemia in diabetic humans.
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Objective To investigate the effects of pulsed electromagnetic fields (PEMFs) of different intensities on bone metabolism in ovariectomized rata. Methods Sixty 10-month-old female Sprague-Dawley rats were randomly divided into a normal group, an ovariectomized control group, a 0. 14 mT group, a 0. 16 mT group, a 0.18 mT group and an estrogen group. All rats except those in the normal group were subjected to bilateral ovariectomy. Beginning one week after the operation, the rats in the 0. 14 mT, 0. 16 mT and 0.18 mT groups were treated with PEMFs at 50 Hz, 60 min daily for 90 days, while those in the estrogen group received estrogen instead. During the experiment, the bone mineral density (BMD) of the whole body was observed dynamically, and local BMDs and biochemical indexes were measured after 3 months of treatment. Results Alkaline phosphatase (ALP) activity in the normal group was significantly lower than in the other groups. Tartrate-resistant acidic phosphatase 5b (TRAP5b)activity was elevated significantly, in the control and 0.14 mT groups compared with the normal group. After 2 months of treatment, whole body BMD was reduced significantly in the 0.14 mT group compared to the normal group. After 3 months of treatment, whole body BMD in the ovariectomized controls and the 0.14 mT group was reduced significantly compared to the normal group, but significantly elevated in the 0. 16 mT, 0.18 mT and estrogen groups when compared to the ovariectomized control group. At the end of 3 months of treatment, the trends in lumbar vertebral BMD were similar to those of the whole body BMD, with the femoral BMD in the ovariectomized group and the 0.14 mT group significantly lower than in the normal group, though the differences among the other groups were not statistically significant. Conclusions PEMF treatment at 50 Hz and 0.16 mT or 0.18 mT can promote bone formation. PEMFs at 50 Hz and 0.14 mT might stimulate bone resorption. An intensity-window effect exists in the action of PEMFs on bone metabolism in ovariectomized rats.
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Objective To observe the effect of pulsed electromagnetic fields (PEMFs) of different intensities on the biomechanical properties of the femur in ovariectomized rats so as to determine the intensity for the best therapeutic efficacy. Methods Fifty female Sprague-Dawley rats were randomly divided into (1) a sham-operated control group (no PEMF treatment) , (2) ovariectomized control group (no PEMF treatment) (3) ovariectomized group Ⅰ (PEMF treatment at 8 Hz and 0.77 mT intensity, 40 min daily for 30 days) (4) ovariectomized group Ⅱ (PEMF treatment at 8 Hz and 3.82 mT intensity, 40 min daily for 30 days) and (5) ovariectomized group Ⅲ( PEMF treatment at 8 Hz and 9.87 mT intensity, 40 min daily for 30 days). Except for the 10 rats of the sham-operated control group, all the others received a standard ovariectomy. Serum estradiol (E2) and the biomechanical properties of one femur (peak load, maximum displacement, maximum energy absorption, maximum stress, maximum strain and modulus of elasticity) were assessed after 30 days of PEMF treatment. Results In group Ⅱ the biomechanical properties of the femur were significantly better than in group Ⅰ or the ovariectomized control group. In groups Ⅰ and Ⅲ the biomechanical properties of the femur were not significantly better than in the sham-operated group. In group Ⅱ the biomechanical properties of the femur were significantly better than in groups Ⅰ or Ⅲ. Conclusion PEMFs at 3.82 mT can improve the biomechanical properties of the femur significantly.
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Objective To observe the effects of pulsed electromagnetic fields (PEMFs) on behavior and mechanical paw withdrawal thresholds (MPWTs) after acute skeletal muscle contusion (ASMC) in rats, and to in-vestigate the application of PEMFs in rats with ASMC during the early stage. Methods Forty-two Sprague-Dawley rats were randomly divided into a PEMF group (P group) , control group (C group) and blank control group ( BC group). ASMC models were set up in groups P and C, and no intervention was applied in the BC group. A PEMF was administered to animals in the P group immediately after the ASMC was inflicted. The behavior of the rats in each group was then observed. The MPWT of each rat was tested 2 days before and 0, 12, and 18 hours after the ASMC was inflicted). Results In the P and C groups, MPWT of the left hind paw at the 12th and 18th hour after ASMC was significantly lower than the baseline pain threshold 2 days before the ASMC. At 18 hours, the MPWT was signifi-cantly higher than at 12 hours in the P group. MPWT at 12 hours in the P group and at both 12 and 18 hours in the C group were significantly lower than in the BC group. MPWT in the P group at 18 hours was significantly higher than in the C group. Conclusions The behavior of rats treated with PEMF immediately after ASMC was improved, and their pain threshold was still elevated 18 hours later.
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Objective To study the effects of uhrashortwave and low frequency pulsed electromagnetic fields on the expression of vascular endothelial growth factor(VEGF) in fracture healing. Methods Fifty-six New Zeal-and rabbits with artificial fractures were randomly divided into 4 groups:a control group,an ultrashortwave group,a low frequency pulsed electromagnetic field group and an ultrashortwave combined with low frequency pulsed electro-magnetic field group(combined group),with 14 in each group.Radiographic evaluation of callus formation and frac-ture healing,pathohistological examination and detection of VEGF expression through immunohistochemical staining were performed at the 1 st,2nd,4th and 6th week after the operation. Results Radiographic examination showed that there was significantly greater callus formation in the combined group than in the other groups throughout the healing process. Pathohistological examination also revealed significantly more cartilage islets and callus formation in the combined group.At the 1 st,2nd and 4th week after the operation,VEGF positive indexes in the combined group were significantly higher than in the other groups. Conclusion Uhrashortwave combined with low frequency pulsed electromagnetic field exposure can up-regulate the expression of VEGF and thus can accelerate fracture healing.
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Objective To study the influence of pulsed electromagnetic fields on the expression of type I collagen by bone marrow mesenchymal stem cells and it's mechanism. Methods The bone marrow mesenchymal stem cells of SD rats were isolated and cultured in vitro.The third passage cells were harvested and exposed to pulsed electromagnetic fields(PEMFs)at 15 Hz and 1 mT 8 h/d for 3 days.A semi-quantitative RT-PCR technique was used to measure the type I collagen mRNA expression;ELISA and immunohistochemitistry techniques were used to measure type I collagen expression.Inhibitors and promoters of the cAMP-dependent protein kinase A(cAMP-PKA)pathway were added.After the cAMP-PKA pathway had been inhibited or promoted,the effects of the PEMF on type I collagen expression were measured again using ELISA and immunohistoehemistry.Results PEMFs at 15 Hz and 1 mT induced significant promotion of the expression of type I collagen(P≤0.01)in comparison with the controls. The type I collagen expression was reduced when the cAMP-PKA pathway inhibitor H-89 was added,and raised when the promoter 8-Br-cAMP was added.Conclusion PEMFs at 15 Hz 1 mT can promote type I collagen expression of bone marrow mesenchymal stem cells.and the effect is correlated with the cAMP-PKA pathway.