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Objective To investigate the effects of constant magnetic field (CMF) on proliferation, apopto-sis and nitric oxide (NO) secretion of rat bone marrow-derived endothelial progenitor cells (EPCs) intervened by C-reactive protein (CRP). Methods EPCs were isolated from rat bone marrow by density gradient centrifugation and cultured on fibronectin-coated dishes. The cells were divided into five groups, i. e., control group, CRP (12 μg/ml) group, CRP plus CMF (0.1, 0. 5, 1.0 mT) groups. Samples were collected 24 hours after incubation. Cell proliferation was measured by MTT chromatometry. Apoptosis rate was detected by flow-cytometry. NO content of culture medium was measured by nitrate reductase method. Results As compared with control group, cell prolifer-ation in CRP group reduced significantly (0. 265±0. 008 vs 0. 316±0. 011, P < 0.05), NO secretion also de-creased significantly [(22.7±4.5) μmol/L vs (37.6±3.8) μmol/L, P < 0.05], cell apoptosis rate elevated sig-nificantly [(10.8±0. 8) % vs (4.2±0.5)% ,P < 0.05]. Cell proliferation in CRP plus 0. 5 mT or 1.0 mT CMF group (0. 295±0. 009,0. 302±0. 010) were much more than those in CRP group (P<0.05), NO secretion contents [(28.3±4.9) μmol/L, (29.2±5.6) μmol/L]were also much more than those in CRP group (P < 0.05) , apopto-sis rate [(7.4±0.5)% ,(6.9±0.6)%]was significantly lower than that in CRP group (P <0.05). Conclusion CMF at intensity of 0.5 mT and 1.0 mT can antagonize the effects of CR, promote proliferation of EPCs and secretion of NO and inhibit apoptosis rate of EPCs.
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Objective To investigate the effect of direct intercell contact on the bone mesenchymal stem cells(MSCs)differentiate into nucleus pulposus cells(NPs)when cocultured with NPs in constant magnetic field.Methods The primary NPs labeled by DAP1 were cocultured with the 3 rd generation of MSCs through direct and indirect intercell contact in the presence or absence of constant magnetic field(0.05,0.10,0.50 and 1.00 mT,respectively). Observation of morphological changes was performed every 24 hours.The method of MTT was employed to evaluate the level of proliferation.The gene expression of collagen Ⅱ,Sox-9 and Aggrecan was measured by using RT-PCR. Results MSCs cocultured with direct intercell contact with the NPs rounded up and presented a round ring-like structure appearance.The expression of marker genes including Collagen type Ⅱ,Aggrecan and Sox-9 were significantly increased when cells cocultured in constant magnetic field of 0.05 mT compared with those without constant magnetic field(P＜0.05).There were no significantly changes with regard to the expression of the above genes in 0.10 mT field(P＞0.05).The growth of NP-like cells was suppressed when the intensity of magnetic field was higher than 0.10 mT(P＜0.05).Conclusion It is suggested that 0.05 mT constant magnetic field and direct intercell contact facilitate differentiation of MSCs into NPs.
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[Objective]To detect the effect of constant magnetic field on metal ion Co2+,Cr3+ induced TNF-? secreted by human mononuclear cells,and to search a method for prevention and treatment of aseptic loosening. [Methods]CoCl2 powder and CrCl3 powder were dissolved in the asepsis injecting water. Mononuclear cells from human peripheral blood,were taken and cultured with Co2+,Cr3+ ions in different magnetic field of 10Gs,100 Gs,1000Gs for 12,24 and 48 hs. There were nine groups:control group,Co2+ group,Cr3+ group,Co2+andCr3+ with various intensities of constant magnetic field,respectively.ELISA method was applied to detect tumor necrosis factor (TNF-?) in serum via the absorbance (A).[Results]Co2+ and Cr3+ ions stimulated human mononuclear cell to secrete TNF-? (P
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Objective To observe the effects of constant magnetic fields (CMF) on angiotensinⅡ (AngⅡ)-stimulated proliferation of human umbilical arterial vascular smooth muscle cells (VSMC). Methods The experimental proliferation models of cultured human umbilical arterial VSMC stimulated with AngⅡ was establishea. The VSMC were cultured under 1 and 5 mT CMF for 48 hrs. Proliferation of the VSMC was detected by MTT and 3H-TdR incorporation method (A-value and cpm-value), and cell cycle was analyzed by flow cytometry. Results The CMF of 1 and 5 mT may antagonize proliferation of VSMC stimulated with AngⅡ, and hold-back VSMC from static phase (G 0/G 1)to DNA synthetic (S) and mitotic phase (G 2/M). Conclusion The study demonstrates that CMF of 1 and 5 mT can significantly inhibit the human VSMC proliferation.
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This paper has reviewed the progress of research on the biological effects of constant magnetic field,including its health impact in animal experiments,occupational exposure and clinical magnetic therapy.The safety exposure limits proposed by scholars at home and abroad were introduced in this review.Standards for safety exposure limits to constant magnetic field need to be considered and set.