The Role of BDNF/TrkB in Odontoblastic DPSC Differentiation and In Vivo Dentin Regeneration

This study investigates the intricate roles of Brain-derived neurotrophic factor (BDNF), its receptor TrkB, and their possible downstream molecule Calcium/calmodulin-dependent protein kinase II (CaMKII) in dentinogenesis, particularly in the context of inflammation. It addresses the link between inflammation and dental tissue regeneration, highlighting enhanced dental pulp stem cell (DPSC)-mediated odontoblastic differentiation under inflammatory conditions induced by lipoteichoic acid (LTA) or tumor necrosis factor-alpha (TNFα). While the role of BDNF in neural tissue repair is well-known, its involvement in dentinogenesis, especially within inflammatory pathways, remains unexplored. The experimental methods involved culturing human DPSCs under odontogenic differentiation conditions treated with BDNF, TrkB agonist (LM22A-4), and/or antagonist (CTX-B), along with TNFα and CaMKII inhibition strategies using siRNA and inhibitors. Immunofluorescence, mineralization assay, ELISA, and quantitative PCR techniques were used to assess the expression of odontogenic markers. The results showed that modulations of BDNF and TrkB significantly influenced early and late stages of odontogenic differentiation, enhancing the expression of key markers involved in dentin matrix formation. TNFα further amplified these effects, with BDNF potentiating its influence, thereby elucidating a regulatory role for BDNF-TrkB signaling in inflammation-induced dentinogenesis. Additionally, the study utilized CRISPR-engineered hDPSCs with enhanced BDNF expression in a pulp-capping mouse model. Western blot analysis and micro-CT imaging confirmed substantial improvements in dentin formation at injury sites. Histological analyses corroborated these findings, confirming the potent role of BDNF-TrkB signaling in promoting odontogenic differentiation and dentinogenesis in vivo. Transcriptomic profiling of TNFα-treated hDPSCs, with and without CTX-B treatment, revealed significant alterations in gene expression profiles associated with immune response, cytokine signaling, and extracellular matrix interactions. This comprehensive analysis unveiled complex regulatory networks modulated by BDNF-TrkB mediated by CaMKII in response to inflammatory stimuli, suggesting potential targets for future therapeutic interventions aimed at enhancing dental tissue repair and regeneration. In conclusion, this study provides novel insights into the synergistic roles of BDNF-TrkB signaling and CaMKII pathways in inflammation-induced dentinogenesis. By elucidating these molecular mechanisms, the research advances our understanding of dental tissue engineering using hDPSCs and identifies potential therapeutic avenues for improving dental tissue repair and regeneration strategies.