Development and characterization of an exosome-loaded biomimetic hydroxyapatite/gelatin scaffold for enhanced dental pulp regeneration.

BACKGROUND/PURPOSE: Regenerative endodontic procedures aim to biologically restore the dentin-pulp complex. Exosomes derived from dental pulp stem cells (D-Exo) have emerged as promising acellular therapeutic agents due to their ability to modulate the regenerative microenvironment. This study evaluated the regenerative potential of D-Exo-loaded hydroxyapatite/gelatin (HAp/Gel) scaffolds in dentin-pulp complex regeneration. MATERIALS AND METHODS: A biomimetic HAp/Gel scaffold was fabricated and characterized for morphology, swelling behavior, degradation, and cytocompatibility. D-Exo were isolated from dental pulp stem cells (DPSCs) and analyzed using transmission electron microscopy (TEM), nanoparticle tracking analysis, and western blotting. Their effects on DPSC proliferation were examined in vitro. In vivo regenerative efficacy was assessed using a rat molar pulp exposure model, followed by micro-computed tomography (μ-CT) at 2 and 4 weeks. RESULTS: The HAp/Gel scaffold exhibited an interconnected porous architecture, controlled degradation, and excellent cytocompatibility. Isolated D-Exo displayed typical vesicular morphology (approximately 117 nm) and expressed CD9, CD63, and CD81. D-Exo enhanced DPSC proliferation in a dose-dependent manner. μ-CT analysis revealed early mineralized tissue formation at 2 weeks and dentin bridge formation at 4 weeks, with more extensive mineralized deposition in the D-Exo-loaded HAp/Gel scaffold group. CONCLUSION: The D-Exo-loaded HAp/Gel scaffold demonstrated favorable biocompatibility and enhanced dentin-pulp complex regeneration in vivo. This biomimetic acellular approach may serve as a promising strategy for future regenerative endodontic applications.