title: Effects of low-intensity electromagnetic fields on the proliferation and differentiation of cultured mouse bone marrow stromal cells.
abstract: BACKGROUND
  Electromagnetic fields (EMFs) used in stem-cell tissue engineering can help elucidate their biological principles.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effects of low-intensity EMFs on cell proliferation, differentiation, and cycle in mouse bone marrow stromal cells (BMSCs) and the in vivo effects of EMFs on BMSC.
  
  
  METHODS
  Harvested BMSCs were cultured for 3 generations and divided into 4 groups. The methylthiotetrazole (MTT) assay was used to evaluate cell proliferation, and alkaline phosphatase activity was measured via a colorimetric assay on the 3rd, 7th, and 10th days. Changes in cell cycle also were analyzed on the 7th day, and bone nodule formation was analyzed on the 12th day. Additionally, the expression of the collagen I gene was examined by reverse transcription-polymerase chain reaction (RT-PCR) on the 10th day. The BMSCs of the irradiated group and the control group were transplanted into cortical bone of different mice femurs separately, with poly(lactic-co-glycolic acid) (PLGA) serving as a scaffold. After 4 and 8 weeks, bone the bone specimens of mice were sliced and stained by hematoxylin and eosin separately.
  
  
  RESULTS
  The results showed that EMFs (0.5 mT, 50 Hz) accelerated cellular proliferation, enhanced cellular differentiation, and increased the percentage of cells in the G(2)/M+S (postsynthetic gap 2 period/mitotic phase + S phase) of the stimulation. The EMF-exposed groups had significantly higher collagen I messenger RNA levels than the control group. The EMF + osteogenic medium-treated group readily formed bone nodules. Hematoxylin and eosin staining showed a clear flaking of bone tissue in the irradiated group.
  
  
  CONCLUSIONS
  Irradiation of BMSCs with low-intensity EMFs (0.5 mT, 50 Hz) increased cell proliferation and induced cell differentiation. The results of this study did not establish a stricter animal model for studying osteogenesis, and only short-term results were investigated. Further study of the mechanism of EMF is needed.
authors.affiliation: Department of Orthopedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhong
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhengjian
authors.initials: Z
authors.lastname: Xu
authors.forename: Rongxin
authors.initials: R
authors.lastname: He
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001854:Bone Marrow Cells / Q000502:physiology / Q000528:radiation effects*; D016026:Bone Marrow Transplantation; D002453:Cell Cycle / Q000528:radiation effects; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics; D004574:Electromagnetic Fields; D005269:Femur / Q000601:surgery; D005434:Flow Cytometry; D015870:Gene Expression; D051379:Mice; D010012:Osteogenesis / Q000502:physiology / Q000528:radiation effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000502:physiology / Q000528:radiation effects*; D054457:Tissue Scaffolds
chemical_list: D003094:Collagen