microRNA-200c Mitigates Pulpitis and Promotes Dentin Regeneration

MicroRNA (miR)-200c enhances osteogenesis, modulates inflammation, and participates in dentin development. This study was to investigate the beneficial potential of miR-200c in vital pulp therapy (VPT) by mitigating pulpitis and promoting dentin regeneration. We explored the miR-200c variations in inflamed pulp tissues from patients with symptomatic irreversible pulpitis and primary human dental pulp-derived cells (DPCs) challenged with P.g. lipopolysaccharide (Pg-LPS). We further assessed the functions of overexpression of miR-200c on odontogenic differentiation, pulpal inflammation, and dentin regeneration in vitro and in vivo. Our findings revealed a noteworthy downregulation of miR-200c expression in inflamed pulp tissues and primary human DPCs. Through the overexpression of miR-200c via transfecting plasmid DNA (pDNA), we observed a substantial downregulation of proinflammatory cytokines interleukin (IL)-6 and IL-8 in human DPCs. Furthermore, this overexpression significantly enhanced the transcript and protein levels of odontogenic differentiation markers, including Runt-related transcription factor (Runx)2, osteocalcin (OCN), dentin matrix protein (DMP)1, and dentin sialophosphoprotein (DSPP). In a rat model of pulpitis induced by Pg-LPS, we demonstrated notable benefits by local application of pDNA encoding miR-200c delivered by CaCO₃-based nanoparticles to reduce pulpal inflammation and promote dentin formation. These results underscore the significant impact of locally applied miR-200c in modulating pulpal inflammation and facilitating dentin repair, showcasing its ability to improve VPT outcomes.