BACKGROUND:Magnetically responsive hydrogels have great advantages in bone tissue engineering,which is more conducive to the minimally invasive and efficient promotion of osteogenesis. OBJECTIVE:To review the application advances of magnetically responsive hydrogels in bone tissue engineering. METHODS:PubMed,Web of Science,WanFang and CNKI databases were used to search relevant literature.The English search terms were"Magnetic Hydrogels,Magnetic Nanoparticles,Superparamagnetic Nanoparticles,Fe3O4,SPIONs,Magnetic Fields,Bone Regeneration,Bone Repair,Bone Tissue Engineering".The Chinese search terms were"Magnetic Hydrogel,Magnetic Nanoparticles,Superparamagnetic Iron Oxide Nanoparticles,Magnetic Field,Iron Oxide Nanoparticles,Bone Regeneration,Bone Reconstruction,Bone Repair,Bone Tissue Engineering".After preliminary screening of all articles according to the inclusion and exclusion criteria,60 articles were finally retained for review. RESULTS AND CONCLUSION:(1)In recent years,due to the emergence of magnetic nanoparticles,more and more magnetic responsive scaffold materials have been developed.Among them,magnetic responsive hydrogels containing iron oxide nanoparticles and superparamagnetic iron oxide nanoparticles have outstanding mechanical properties and good biocompatibility.It can quickly respond to the external magnetic field and provide the magnetic-mechanical signals needed for seed cells to form bone.(2)Magnetic-responsive hydrogel can be used as a carrier to accurately regulate the release time of growth factors.(3)Under the three-dimensional microenvironment culture platform based on magnetically responsive hydrogel,the magnetic force at the interface between the magnetic response hydrogel and cells can activate cell surface sensitive receptors,enhance cell activity,and promote the integration of new bone and host bone.(4)The injectable magnetically responsive hydrogel can be used in the field of magnetic hyperthermia and biological imaging of bone tumors.(5)At present,magnetically responsive hydrogels are expected to mimic the anisotropic layered structure observed in natural bone tissue.However,most of the studies on magnetically responsive hydrogels focus on in vitro studies,and the mechanism of interaction between magnetically responsive hydrogels and the local microenvironment in vivo is still insufficient.(6)Therefore,based on the successful application of magnetic nanoparticles in magnetic resonance imaging,it is expected to optimize the properties of magnetic nanoparticles in the future to construct magnetic responsive hydrogels with suitable degradation properties,mechanical properties,and vascular functionalization,which can monitor changes in vivo in real time.