Quercetin-loaded mesoporous nano-delivery system remodels osteoimmune microenvironment to regenerate alveolar bone in periodontitis via the miR-21a-5p/PDCD4/NF-κB pathway.

BACKGROUND: Impaired osteo-/angiogenesis, excessive inflammation, and imbalance of the osteoimmune homeostasis are involved in the pathogenesis of the alveolar bone defect caused by periodontitis. Unfortunately, there is still a lack of ideal therapeutic strategies for periodontitis that can regenerate the alveolar bone while remodeling the osteoimmune microenvironment. Quercetin, as a monomeric flavonoid, has multiple pharmacological activities, such as pro-regenerative, anti-inflammatory, and immunomodulatory effects. Despite its vast spectrum of pharmacological activities, quercetin's clinical application is limited due to its poor water solubility and low bioavailability. RESULTS: In this study, we fabricated a quercetin-loaded mesoporous bioactive glass (Quercetin/MBG) nano-delivery system with the function of continuously releasing quercetin, which could better promote the bone regeneration and regulate the immune microenvironment in the alveolar bone defect with periodontitis compared to pure MBG treatment. In particular, this nano-delivery system effectively decreased injection frequency of quercetin while yielding favorable therapeutic results. In view of the above excellent therapeutic effects achieved by the sustained release of quercetin, we further investigated its therapeutic mechanisms. Our findings indicated that under the periodontitis microenvironment, the intervention of quercetin could restore the osteo-/angiogenic capacity of periodontal ligament stem cells (PDLSCs), induce immune regulation of macrophages and exert an osteoimmunomodulatory effect. Furthermore, we also found that the above osteoimmunomodulatory effects of quercetin via macrophages could be partially blocked by the overexpression of a key microRNA--miR-21a-5p, which worked through inhibiting the expression of PDCD4 and activating the NF-κB signaling pathway. CONCLUSION: In summary, our study shows that quercetin-loaded mesoporous nano-delivery system has the potential to be a therapeutic approach for reconstructing alveolar bone defects in periodontitis. Furthermore, it also offers a new perspective for treating alveolar bone defects in periodontitis by inhibiting the expression of miR-21a-5p in macrophages and thereby creating a favorable osteoimmune microenvironment.

Accuracy of Mandibular Reconstruction with a Vascularised Iliac Flap Using 3D Templates: a Systematic Review.

OBJECTIVE: To conduct a systemic review for guidance regarding the application of templates in mandibular reconstruction with vascularised iliac flaps. METHODS: By searching PubMed, EMBASE and the Cochrane Library and collecting relevant literature, information about the types and accuracy of templates was extracted. Data relating to surgical time were also included for further analysis. RESULTS: Eight studies were included. The data analysis showed that the accuracy of operations with templates was higher than that of conventional surgery. The mean deviation was between 0.70 and 3.72 mm. The operational time was shortened to 314.4 minutes and the graft ischemic time was reduced to 15.6 to 26.8 minutes. Application of functional or specifically designed templates can improve the accuracy and shorten surgical time. CONCLUSION: Templates can increase the accuracy and efficiency of mandibular reconstruction with vascularised iliac flaps, which will benefit patients' prognosis and subsequent functional restoration. Further studies should be conducted into application of templates to improve the accuracy of reconstructions.