Elastic Membranes Induce Macrophage-Mediated Pmscs Activation For Bone Regeneration

Traditional collagen membranes used in guided bone regeneration (GBR) act only as passive barriers, lacking active bone-regenerative properties. This study explores optimizing collagen membranes' elastic modulus to regulate macrophages, guide immune microenvironments, and activate periosteal mesenchymal stem cells (PMSCs) for improved bone regeneration. Collagen membranes underwent 0, 3, and 7 freeze-thaw cycles to modify mechanical properties. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyzed structural changes, including pore density and elastic modulus. Macrophage responses, such as polarization, adhesion, and secretion, were evaluated. A tri-culture system assessed immune microenvironment effects on PMSC proliferation, migration, and differentiation. Freeze-thaw cycles increased pore density and elastic modulus (Figure 1A). Medium elastic modulus membranes suppressed immune responses but enhanced macrophage adhesion and migration, whereas high elastic modulus membranes boosted secretion but reduced sensitivity to stimuli. Gradient elastic modulus membranes regulated macrophage polarization, shaping immune microenvironments (Figure 1B), which enhanced PMSC proliferation, migration, and osteogenic differentiation (Figure 1C). Freeze-thaw cycling optimizes collagen membrane elasticity, precisely regulating macrophage microenvironments and activating PMSCs functions.