Effect of static magnetic field on bone and its molecular mechanism

As a non-invasive physical factor, static magnetic field (SMF) with a constant magnetic field strength and direction, has a long history of basic and clinical research in bone biology. Animal experiments and clinical studies demonstrate that local or systemic exposure to SMF can prevent osteoporosis, increase bone mass and bone density. Fracture nonunion is a challenge for surgeons. SMF with certain magnetic field intensity can increase fracture healing rate and shorten fracture healing time. Bone defect is a shortage of bone due to trauma or surgery. Studies have shown that exposure to a SMF near the implant can effectively promote bone defect repair. In dental defects, direct magnetic implants can better promote bone formation around the implant, enhance the combination of the implant and bone, and increase the stability of the implant. In addition, the development and pain of osteoarthritis can be suppressed and relieved by SMFs. The effect of SMF on bone diseases may be associated with its regulation on the proliferation and differentiation of bone cells. In vitro, although different studies display that SMFs have different effects on the proliferation of bone marrow mesenchymal stem cells and osteoblasts, the same conclusions are shown that osteogenesis can be induced by SMFs. In contrast, the osteoclastic differentiation and bone resorption activity are inhibited by SMFs. Furthermore, SMF is also possible by affecting bone cells, cartilage cells and endothelial cells involved in remodeling and repair of bone tissue. For the mechanism of SMF affecting bone metabolism, existing studies have revealed that SMFs promote the expression and secretion of cytokines, regulate the expression of cell signal molecules, cause rearrangement of cytoskeleton, change the physical characteristics of cell membranes, affect the concentration and distribution of intracellular calcium ions, and regulate cellular iron metabolism. There are still many challenges in the application of SMF in bone biology. First, more basic experiments need to be performed to further determine the biological effects of SMF on bone. Second, it is necessary to explore the mechanism of the effect of SMF on bone from a physical and chemical level. Third, more clinical experimental data are needed to support the therapeutic effect of SMF on bone diseases. Finally, we should strengthen cooperation between basic research scientists and enterprises that manufacture magnetic therapy products to promote the application of SMF in the field of orthopedics.