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 alpha V beta 3/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.

Automated summary

In this study, a magnetic magnesium-loaded bone scaffold was prepared by introducing magnetite nanoparticle into the poly(l-lactic acid)/magnesium oxide composite. By enhancing the activity of Mg2+ channel protein (MAGT1) on the surface of bone marrow mesenchymal stem cells (rBMSCs) through the magnetic torque effect under the static magnetic field (SMF), the scaffold promoted the capture of Mg2+ and induced osteogenesis. In vitro and in vivo experiments showed that the magnetic scaffold accelerated the inflow of Mg2+ from the surrounding microenvironment, improving cellular activities, osteogenesis-related gene expression, and mineralization.