title: Moderate-intensity rotating magnetic fields do not affect bone quality and bone remodeling in hindlimb suspended rats.
abstract: Abundant evidence has substantiated the positive effects of pulsed electromagnetic fields (PEMF) and static magnetic fields (SMF) on inhibiting osteopenia and promoting fracture healing. However, the osteogenic potential of rotating magnetic fields (RMF), another common electromagnetic application modality, remains poorly characterized thus far, although numerous commercial RMF treatment devices have been available on the market. Herein the impacts of RMF on osteoporotic bone microarchitecture, bone strength and bone metabolism were systematically investigated in hindlimb-unloaded (HU) rats. Thirty two 3-month-old male Sprague-Dawley rats were randomly assigned to the Control (n = 10), HU (n = 10) and HU with RMF exposure (HU+RMF, n = 12) groups. Rats in the HU+RMF group were subjected to daily 2-hour exposure to moderate-intensity RMF (ranging from 0.60 T to 0.38 T) at 7 Hz for 4 weeks. HU caused significant decreases in body mass and soleus muscle mass of rats, which were not obviously altered by RMF. Three-point bending test showed that the mechanical properties of femurs in HU rats, including maximum load, stiffness, energy absorption and elastic modulus were not markedly affected by RMF. µCT analysis demonstrated that 4-week RMF did not significantly prevent HU-induced deterioration of femoral trabecular and cortical bone microarchitecture. Serum biochemical analysis showed that RMF did not significantly change HU-induced decrease in serum bone formation markers and increase in bone resorption markers. Bone histomorphometric analysis further confirmed that RMF showed no impacts on bone remodeling in HU rats, as evidenced by unchanged mineral apposition rate, bone formation rate, osteoblast numbers and osteoclast numbers in cancellous bone. Together, our findings reveal that RMF do not significantly affect bone microstructure, bone mechanical strength and bone remodeling in HU-induced disuse osteoporotic rats. Our study indicates potentially obvious waveform-dependent effects of electromagnetic fields-stimulated osteogenesis, suggesting that RMF, at least in the present form, might not be an optimal modality for inhibiting disuse osteopenia/osteoporosis.
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Da
authors.initials: D
authors.lastname: Jing
authors.affiliation: Department of Endocrinology, Xijing hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Cai
authors.affiliation: Institute of Orthopaedics, Xijing hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Guanghao
authors.initials: G
authors.lastname: Shen
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Zhai
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Shichao
authors.initials: S
authors.lastname: Tong
authors.affiliation: Department of Nursing, Fourth Military Medical University, Xi'an, China.
authors.forename: Qiaoling
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Kangning
authors.initials: K
authors.lastname: Xie
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Tang
authors.affiliation: Department of Medical Engineering, PLA No. 323 Hospital, Xi'an, China.
authors.forename: Xinmin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Maogang
authors.initials: M
authors.lastname: Jiang
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Erping
authors.initials: E
authors.lastname: Luo
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001835:Body Weight / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D001842:Bone and Bones / Q000502:physiology*; D024042:Collagen Type I / Q000097:blood; D019417:Hindlimb Suspension / Q000502:physiology*; D060526:Magnetic Fields; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D015675:Osteocalcin / Q000097:blood; D010012:Osteogenesis / Q000502:physiology; D010455:Peptides / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin