title: [Effects of static magnetic field at different times on the proliferation and differentiation of osteoblasts in vitro].
abstract: OBJECTIVE
  To investigate the effect of exposure to static magnetic fields (SMFs) of 3.9 mT on proliferation and differentiation of osteoblasts in vitro.
  
  
  METHODS
  The newborn rat calvarial osteoblasts were isolated by enzyme digestion and randomly divided into 9 groups after one passage. The intensity of the SMFs was 3.9 mT. The cells were exposed in the SMFs for 0 (control group), 0.5, 1.0, 1.5, 2.0, 2.5, 3, 3.5 and 4.0 h groups respectively. They were observed under the contrast phase microscope each day. After 48 h, cell proliferation was assayed by MTT method. The alkaline phosphatase (Alkaline Phosphatase, ALP) activities and calcium content were measured after 3, 6, 9, and 12 days exposed with SMFs. The ALP positive colonies were histochemically stained after 8 days and the calcified nodules were stained by Alizarin Bordeaux after 10 days; BMP-2, Runx-2 and Opg mRNA expression were measured after SMFs treatment in 0, 24, 48 and 72 h.
  
  
  RESULTS
  Contrast with control group, all SMFs groups enhanced cell proliferation (P < 0.01 or P < 0.05), and they promoted maturation and mineralization of the osteoblasts. The results showed that SMFs improved the ALP activity, promoted calcium content, boost BMP-2, Runx -2 and Opg mRNA expression.
  
  
  CONCLUSIONS
  The cells exposed to the SMFs of 3.9 mT at 2.5 h apparently promote proliferation and differentiation of osteoblasts in vitro.
authors: Institute of Orthopaedics, Lanzhou General Hospital of PLA, Lanzhou 730050, Gansu, China.
authors: Jia-Qi
authors: JQ
authors: Wang
authors: Bao-Feng
authors: BF
authors: Ge
authors: Xiao-Ni
authors: XN
authors: Ma
authors: Jian
authors: J
authors: Zhou
authors: Xiao-Yu
authors: XY
authors: Guo
authors: Ke-Ming
authors: KM
authors: Chen
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics; D060526:Magnetic Fields; D010006:Osteoblasts / Q000502:physiology / Q000528:radiation effects*; D053244:Osteoprotegerin / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D055396:Bone Morphogenetic Protein 2; D050659:Core Binding Factor Alpha 1 Subunit; D053244:Osteoprotegerin; C493717:Runx2 protein, rat; D002118:Calcium