title: Effects of 50 Hz sinusoidal electromagnetic fields of different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts.
abstract: Electromagnetic fields (EMFs) have been used clinically to slow down osteoporosis and promote fracture healing for many years. However, the underlying action mechanisms and optimal parameters of the EMF applications are unclear. In this study, we investigated the effects of treatment for different durations with 50 Hz sinusoidal electromagnetic fields (SEMFs) at different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts. Osteoblasts isolated from neonatal rats were treated with SEMFs (50 Hz at 0.9 mT-4.8 mT, 0.3 mT interval, 30 min/day up to 15 days). Compared to untreated control, SEMFs inhibited osteoblast proliferation (after 3 days' treatment) but increased alkaline phosphatase (ALP) activity (after treatment for 9 days) from 0.9 mT to 1.8 mT, declined from 1.8 mT until 3.0 mT, and then increased again from 3.0 mT to 3.6 mT and decreased once again from 3.6 mT to 4.8 mT. Numbers of colonies stained positive for ALP after 8 days and mineralized nodules stained by Alizarin red after 10 days showed the same bimodal tendency as with the ALP activity, with two peaks at 1.8 mT and 3.6 mT. SEMFs also bimodally increased Runx-2, Col1α2 and Bmp-2 mRNA expression levels in osteoblasts at 12, 24 and 96 h after exposure. The results indicated that while exposure to 50 Hz SEMFs inhibits the osteoblast proliferation, it significantly promotes differentiation and mineralization potentials of osteoblasts in an intensity-dependent manner with peak activity at 1.8 mT and 3.6 mT.
authors: Institute of Orthopaedics, Lanzhou General Hospital, [corrected] Lanzhou Command of CPLA, Lanzhou 730050, People's Republic of China. zhoujian715412@126.com
authors: Jian
authors: J
authors: Zhou
authors: Lei-Guo
authors: LG
authors: Ming
authors: Bao-Feng
authors: BF
authors: Ge
authors: Jia-Qi
authors: JQ
authors: Wang
authors: Rui-Qing
authors: RQ
authors: Zhu
authors: Zhe
authors: Z
authors: Wei
authors: Hui-Ping
authors: HP
authors: Ma
authors: Cory J
authors: CJ
authors: Xian
authors: Ke-Ming
authors: KM
authors: Chen
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002113:Calcification, Physiologic / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D049109:Cell Proliferation; D048430:Cell Shape; D004574:Electromagnetic Fields; D004587:Electrophoresis, Agar Gel; D005786:Gene Expression Regulation; D010006:Osteoblasts / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D000469:Alkaline Phosphatase