SHED-Derived Exosomes Attenuate Osteoclastogenesis to Ameliorate Apical Periodontitis in Rats.

INTRODUCTION AND AIMS: Apical periodontitis (AP) is a prevalent oral disease characterized by periapical tissue inflammation and alveolar bone resorption. This study investigated the inhibitory effects of human exfoliated deciduous teeth-derived exosomes (SHED-EXOs) on osteoclastogenesis, elucidated the underlying mechanisms, and evaluated their protect efficacy in AP rat models, aiming to provide novel adjunctive therapies to augment root canal treatment. METHODS: In vitro, bone marrow-derived monocytes (BMMs) underwent osteoclastogenesis were cultured with graded concentrations of SHED-EXOs (0-20 μg/mL). Tartrate-resistant acid phosphatase staining and podosome belt immunofluorescence assays were performed to assess osteoclast formation. Osteoclast-related protein and gene expression were quantified. Exosomal proteomics and osteoclast transcriptomic sequencing were integrated with bioinformatic analysis to identify pivotal signalling pathways. In vivo, AP rat model were developed and received localized intrapulpal delivery of hydrogel-encapsulated SHED-EXOs. The therapeutic efficacy was evaluated through micro-CT, histological staining, and immunohistochemical analysis. RESULTS: SHED-EXOs concentration-dependently suppressed osteoclast formation with downregulation of NFATC1/CTSK/RANKL. Multiomics analysis revealed enrichment of PI3K-AKT signalling, and mechanistically, SHED-EXOs may inhibit osteoclastogenesis by activating PI3K-AKT pathway. In vivo, local delivery of SHED-EXOs via hydrogel significantly reduced the number of osteoclasts, decreased the expression of NFATC1 as well as RANKL, activated PI3K-AKT signalling, attenuated bone resorption, and restored periapical structure. CONCLUSION: SHED-EXOs may serve as a promising cell-free adjunctive strategy for AP, inhibiting osteoclasts potentially via PI3K-AKT activation. CLINICAL RELEVANCE: This study developed a novel cell-free therapeutic strategy based on SHED-EXOs to enhance the treatment efficacy for AP. SHED-EXOs effectively inhibit osteoclast activity, attenuate bone resorption, and promote periapical bone tissue repair. The underlying mechanism involves the activation of the PI3K-AKT pathway. Combined with a localized hydrogel delivery system, this strategy paves the way for innovative approaches in regenerative endodontics.