Biomimetic Structural Protein Based Magnetic Responsive Scaffold for Enhancing Bone Regeneration by Physical Stimulation on Intracellular Calcium Homeostasis

Bone matrix has distinct architecture and biochemistry which present a barrier on synthesizing bone-mimetic regenerative scaffolds. To mimic the natural structures and components of bone, we prepared the biomimetic structural decellularized extracellular matrix (ECM)/regenerated silk fibroin (RSF) scaffolds incorporated with magnetic nanoparticles (MNP) using a facile synthetic methodology. The ECM/RSF/MNP scaffold is hierarchically organized and interconnected porous structure with silk fibroin twined on the collagen nanofibers, mimicking the bone minimum unit morphology. The scaffold demonstrated saturation magnetization due to the presence of MNP, along with good cytocompatibility. Moreover, the β-sheet crystalline domain of RSF and the chelated magnetic nanoparticles could mimic the deposition of hydroxyapatite and enhance compressive modulus of the scaffold by approximately 20%. The results indicated that an external static magnetic field (SMF) with a magnetic responsive scaffold effectively promoted cell migration, osteogenic differentiation, neogenesis of endotheliocytes in vitro and new bone formation in a critical-size femur defect rat model. RNA sequencing revealed that the molecular mechanisms underlying this osteogenic effect involve calsequestrin-2-mediated Ca 2+ release from the endoplasmic reticulum to activate Ca 2+ /calmodulin/calmodulin-dependent kinase II signaling axis. Collectively, bionic magnetic scaffolds with SMF stimulation provide a potent strategy for bone regeneration through internal structural cues, biochemical composition and external physical stimulation on intracellular Ca 2+ homeostasis. This article is protected by copyright. All rights reserved