Moderate Static Magnetic Fields Prevent Bone Architectural Deterioration and Strength Reduction in Ovariectomized Mice

Substantial studies have revealed the capacity of moderate-intensity static magnetic fields (SMFs) on promoting osteogenesis and inhibiting bone resorption. However, it is unknown whether moderate SMF can resist the deterioration of bone microarchitecture and strength induced by the reduction of estrogen in animal model for postmenopausal osteoporosis. Herein, the efficiency of moderate SMF of 0.2~0.4 T and SMF of 0.6 T on bone mineral density (BMD) and bone mineral content (BMC), bone microarchitecture, bone strength, and histological bone turnover was systematically investigated in ovariectomized (OVX) mice. OVX mice and sham mice were subjected to SMF exposure continuously for four weeks. Dual-energy X-ray absorptiometry (DEXA) data showed SMF prevented the reduction of BMD and BMC in OVX mice. Micro-computed tomography (Micro-CT) results revealed that SMF ameliorated the deterioration of trabecular and cortical bone microarchitecture. Three-point bending test showed that SMF mitigated OVX-induced reduction in femoral mechanical properties, including stiffness, ultimate stress, and elasticity modulus. Moreover, bone histochemical analysis demonstrated that SMF decreased osteoclast formation in cancellous bone and cortical bone, while SMF increased osteoblast formation in trabecular bone. Together, these results demonstrate that moderate SMF alleviated menopause-induced bone loss effectively, and imply that moderate SMF might become a potential biophysical treatment modality for postmenopausal osteoporosis.