Moderate static magnetic field promotes fracture healing and regulates iron metabolism in mice

Abstract

Abstract Background Fracture is a prevalent orthopedic disease. Static magnetic fields (SMFs) are known to aid in maintaining bone health, but the effect and mechanism on fracture is still unclear. This study is aim to investigate the effect of moderate static magnetic fields (MMFs) on bone structure and metabolism during fracture healing. Methods Eight-week-old male C57BL/6J mice were fractured at tibia, and following treatment under geomagnetic field (GMF) and MMF. The microarchitecture and mechanical properties were examined by micro-computed tomography (Micro-CT), and 3-point bending. endochondral ossification and bone remodeling were evaluated by bone histomorphometric and serum biochemical assay. Additionally, the atomic absorption spectroscopy and ELISA were used to detect the effect of MMF on iron metabolism in mice. Results MMF exposure increased bone mineral density (BMD), bone volume per tissue volume (BV/TV), mechanical properties, and proportion of mineralized bone matrix of the callus, and reduced the proportion of cartilage in the callus area. Meanwhile, MMF exposure increased the number of osteoblasts in callus on the 14th day and reduced the number of osteoclasts on the 28th day of fracture healing. Furthermore, MMF exposure increased PINP and OCN levels, and reduced the TRAP-5b and β-CTX levels in serum. The MMF exposure reduced liver and callus’s iron content and serum ferritin, while increasing the serum hepcidin concentration. Conclusions MMF exposure could accelerate fracture healing via promote the endochondral ossification and bone formation, while regulating systemic iron metabolism during fracture healing. This investigation indicates that MMF could be used as a physical therapy for fractures.