Cembgn-Loaded Hydrogel Regulates Macrophage Polarization For Bone Repair

Bone defects pose challenges due to limited osteogenic activity, immunomodulation, and mechanical stability in current grafting strategies. M1/M2 polarization dynamics are critical for bone regeneration; M1 prolongation or M2 deficiency causes chronic inflammation and delayed healing. MBGNs are biocompatible and osteogenic, promoting bone repair through ion release (Si⁴⁺, Ca²⁺) and host-bone bonding. Cerium doping boosts antioxidant capacity, M2 polarization, and a pro-regenerative immune microenvironment. However, powder-form Ce-MBG lacks space-maintenance for large/irregular defects. To address this, we combined Ce-MBG with a thermosensitive chitosan hydrogel (CH-GP), which offers injectability and moldability by transitioning from liquid to gel at physiological conditions. Ce-MBG nanoparticles were synthesized via a sol-gel method and integrated into a thermosensitive chitosan hydrogel optimized for degradation, mechanical strength, and ion release. In vitro assessments evaluated time-dependent M1→M2 polarization, osteogenesis, and angiogenesis. In vivo efficacy was tested in rat cranial defect model (8-week male rats). Micro-CT and histology assessed bone repair. The composite hydrogel combines Ce-MBG’s osteogenic/anti-inflammatory properties with chitosan’s temperature-sensitive behavior, promoting M1→M2 polarization through Ce/Si/Ca release, enhancing osteogenesis and stability in vitro/in vivo. This material offers a promising bone repair strategy. This study combines Ce-MBG with a thermosensitive hydrogel, synchronizing early M1→M2 polarization and osteogenesis via bioactive ion release. Results show the hydrogel’s biocompatibility, immunomodulation, and enhanced bone regeneration in vitro/in vivo, offering a promising bone repair strategy.