Magnetic Field Boosts the Transmembrane Transport Efficiency of Magnesium Ions from PLLA Bone Scaffold

In the system of magnesium-loaded scaffolds, the effect of magnesium ions (Mg²⁺ ) on the osteogenesis induction is restricted due to the low transmembrane transport efficiency of Mg²⁺ into the cell, which limits the application for bone defect repair. Inspired by the fact that magnetic field can regulate ion channel proteins on the cell membrane, magnetite nanoparticle is introduced into the poly (l-lactic acid) /magnesium oxide composite in this study, and a magnetic magnesium-loaded bone scaffold is prepared via selective laser sintering . Notably, the activities of the Mg²⁺ channel protein (MAGT1) on the membrane of bone marrow mesenchymal stem cells (rBMSCs) are enhanced via magnetic torque effect (via integrin αV β3/actin), under the action of static magnetic field (SMF), which promoted rBMSCs to capture Mg²⁺ in the microenvironment and induced osteogenesis. In vitro experiments showed that the magnetic magnesium-loaded scaffold, under the action of SMF, can accelerate the inflow of Mg²⁺ from surrounding microenvironment, which improved cellular activities, osteogenesis-related gene expression (ALP, Runx2, OCN, and OPN), and mineralization. Besides, in vivo skull defect repair experiments showed that the scaffolds possessed good ability to promote bone differentiation and new bone regeneration.