Mesenchymal Stem Cells-Derived Exosomes Combined With Bone Grafts Ameliorate Bone Regeneration in Mandibular Defects

Although scaffold materials serve as effective bone substitutes for mandibular reconstruction, their high resorption and biodegradation rates decrease the success of the therapeutic effect. This study aims to explore the bone regenerative potential of bovine-derived osteoid matrix xenografts coupled with cell-free treatments. The study was conducted as a randomized in vivo experiment to repair critical-sized defects in rabbit mandibles. Two treatment groups were established with 10 rabbits: the right hemimandibles were reconstructed with xenograft (control), and the left hemimandibles were reconstructed with dental pulp stem cell (DPSCs)-derived exosomes soaked xenograft (experimental group) within the same rabbit. Micro-computed tomography and histologic analysis were performed at 4 weeks postoperatively. The histopathologic analysis revealed a significant difference in new bone formation scores between the experimental group (4.87±0.78) and the control group (2.87±0.41). Although the micro-computer tomography analysis did not show a statistically significant difference in new bone volume and surface between the groups, it did reveal that the experimental group had greater bone mineral density, trabecular thickness, and separation. The combination of DPSCs-derived exosomes and xenografts proved to be a promising strategy for enhancing new bone formation and regenerative scores in repairing critical-size defects in rabbit mandibles.