New frontiers in salivary extracellular vesicles: transforming diagnostics, monitoring, and therapeutics in oral and systemic diseases.

Salivary extracellular vesicles (EVs) have emerged as key tools for non-invasive diagnostics, playing a crucial role in the early detection and monitoring of diseases. These EVs surpass whole saliva in biomarker detection due to their enhanced stability, which minimizes contamination and enzymatic degradation. The review comprehensively discusses methods for isolating, enriching, quantifying, and characterizing salivary EVs. It highlights their importance as biomarkers in oral diseases like periodontitis and oral cancer, and underscores their potential in monitoring systemic conditions. Furthermore, the review explores the therapeutic possibilities of salivary EVs, particularly in personalized medicine through engineered EVs for targeted drug delivery. The discussion also covers the current challenges and future prospects in the field, emphasizing the potential of salivary EVs in advancing clinical practice and disease management.

The oral microbiome in autoimmune diseases: friend or foe?

The human body is colonized by abundant and diverse microorganisms, collectively known as the microbiome. The oral cavity has more than 700 species of bacteria and consists of unique microbiome niches on mucosal surfaces, on tooth hard tissue, and in saliva. The homeostatic balance between the oral microbiota and the immune system plays an indispensable role in maintaining the well-being and health status of the human host. Growing evidence has demonstrated that oral microbiota dysbiosis is actively involved in regulating the initiation and progression of an array of autoimmune diseases.Oral microbiota dysbiosis is driven by multiple factors, such as host genetic factors, dietary habits, stress, smoking, administration of antibiotics, tissue injury and infection. The dysregulation in the oral microbiome plays a crucial role in triggering and promoting autoimmune diseases via several mechanisms, including microbial translocation, molecular mimicry, autoantigen overproduction, and amplification of autoimmune responses by cytokines. Good oral hygiene behaviors, low carbohydrate diets, healthy lifestyles, usage of prebiotics, probiotics or synbiotics, oral microbiota transplantation and nanomedicine-based therapeutics are promising avenues for maintaining a balanced oral microbiome and treating oral microbiota-mediated autoimmune diseases. Thus, a comprehensive understanding of the relationship between oral microbiota dysbiosis and autoimmune diseases is critical for providing novel insights into the development of oral microbiota-based therapeutic approaches for combating these refractory diseases.

Engineering exosomes and biomaterial-assisted exosomes as therapeutic carriers for bone regeneration.

Mesenchymal stem cell-based therapy has become an effective therapeutic approach for bone regeneration. However, there are still limitations in successful clinical translation. Recently, the secretome of mesenchymal stem cells, especially exosome, plays a critical role in promoting bone repair and regeneration. Exosomes are nanosized, lipid bilayer-enclosed structures carrying proteins, lipids, RNAs, metabolites, growth factors, and cytokines and have attracted great attention for their potential application in bone regenerative medicine. In addition, preconditioning of parental cells and exosome engineering can enhance the regenerative potential of exosomes for treating bone defects. Moreover, with recent advancements in various biomaterials to enhance the therapeutic functions of exosomes, biomaterial-assisted exosomes have become a promising strategy for bone regeneration. This review discusses different insights regarding the roles of exosomes in bone regeneration and summarizes the applications of engineering exosomes and biomaterial-assisted exosomes as safe and versatile bone regeneration agent delivery platforms. The current hurdles of transitioning exosomes from bench to bedside are also discussed.

KLF9 Promotes Osteogenic Differentiation of Dental Stem Cells by Negatively Regulating Notch1 Mediated Signaling Pathway.

BACKGROUND: Human dental stem cells (DSCs) are excellent sources of cells for treating dental and craniofacial diseases. However, the mechanisms regulating DSC osteogenic differentiation are still unclear. In this study, we aimed to determine the role of Krüppel-like factor 9 (KLF9) in regulating the biological functions of DSCs and explore the underlying molecular mechanisms. METHODS: Bioinformatic analyses, quantitative real-time polymerase chain reaction (qRT‒PCR) and Western blotting were performed to determine the KLF9 level during osteogenic differentiation of DSCs. The effects of KLF9 depletion or overexpression on DSC osteogenic differentiation were then evaluated. The osteogenic potential and associated mineralized nodule-forming activities of DSCs were monitored via Alizarin red S staining and quantitative analyses of osteogenic markers. The regulatory effect of KLF9 on the Notch1 signaling pathway was analyzed by luciferase reporter assays. RESULTS: KLF9 mRNA expression was consistently increased during mesenchymal stem cell osteogenic differentiation in multiple public datasets, and our qRT‒PCR and Western blotting data further validated this finding. In addition, KLF9 depletion promoted proliferation and suppressed osteogenic differentiation of DSCs, while enforced expression of KLF9 promoted the DSC osteogenic potential. Mechanistically, KLF9 negatively regulated the Notch1-mediated signaling pathway by directly binding to the Notch1 promoter. More importantly, Notch1 inhibition/overexpression partially rescued the suppressive/enhancing effects of KLF9 depletion/overexpression on the osteogenic differentiation of DSCs, indicating that Notch1 is a functional downstream target of KLF9. CONCLUSIONS: In summary, our results strongly demonstrate that KLF9 is a crucial transcription factor that controls the osteogenic differentiation of DSCs by negatively regulating the Notch1 signaling pathway.

Translational and Clinical Applications of Dental Stem Cell-Derived Exosomes.

Mesenchymal stem cells (MSCs) are promising seed cells in tissue repair and regeneration due to their featured properties of self-renewal and multipotency. However, a growing body of evidence has demonstrated that MSCs exert biological functions mainly through secreting exosomes. Exosomes, which contain RNA, proteins, lipids, and metabolites, are new players in regulating many fundamental processes and play important roles in regenerative medicine. Exosomes not only mimic the effects of their parent cells but also possess many advantages such as high drug loading capacity, low immunogenicity, excellent biocompatibility, and low side effects. Currently, a total of 6 different dental stem cells (DSCs) including dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHEDs), periodontal ligament stem cells (PDLSCs), dental follicle progenitor cells (DFPCs), stem cells from apical papilla (SCAPs) and gingival mesenchymal stem cells (GMSCs) have been isolated and identified. DSC-derived exosomes (DSC-Exos) are actively involved in intercellular communication, anti-inflammation, osteogenesis, angiogenesis, immunomodulation, nurturing neurons, and promoting tumor cell apoptosis. In this review, we will critically review the emerging role and clinical application potential of DSC-Exos.