Leukotriene B 4 Loaded in Microspheres Regulate the Expression of Genes Related to Odontoblastic Differentiation and Biomineralization by Dental Pulp Stem Cells

Background: Leukotriene B4 (LTB4) is a potent lipid mediator that stimulate the immune response. Because dental pulp inflammation and dentin repair are intrinsically related responses, the aim of this research was to investigate the potential of LTB4 in inducing differentiation of dental pulp stem cells. Methods: Microspheres (MS) loaded with LTB4 were prepared using an oil emulsion solvent extraction evaporation process and sterility, characterization, efficiency of LTB4 encapsulation and in vitro LTB4 release assay were investigated. Mouse dental pulp stem cells (OD-21) were stimulated with soluble LTB4 or MS loaded with LTB4 (0.01 and 0.1 μM). Cytotoxicity and cell viability was determined by lactate dehydrogenase (LDH) and MTT (methylthiazol tetrazolium) assays . Gene expression were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) after 3, 6, 24, 48 and 72 h. Results: Mineralized nodule formation was assessed after 28 days of OD-21 cell stimulation with LTB4. Groups were compared using the one-way ANOVA test followed by Dunnett's post-test (α = 0.05). Treatment with LTB4 or MS loaded with LTB4 (0.01 and 0.1 micrometer- μM) were not cytotoxic to OD-21 cells. Treatment with LTB4 modulated the expression of the Ibsp (integrin binding sialoprotein) and Runx2 (runt-related transcription factor 2) genes differently depending on the experimental period analyzed. Interestingly LTB4 loaded in microspheres (0.1 μM) allowed long term dental pulp cell differentiation and biomineralization. LTB4 loaded in MS was not cytotoxic and induced an odontoblastic cell phenotype differentiation. Conclusion: These findings shed light on a novel pharmacological strategy to induce dental pulp cell differentiation.

Periodontal and Dental Pulp Cell-Derived Small Extracellular Vesicles: A Review of the Current Status

Extracellular vesicles (EVs) are membrane-bound lipid particles that are secreted by all cell types and function as cell-to-cell communicators through their cargos of protein, nucleic acid, lipids, and metabolites, which are derived from their parent cells. There is limited information on the isolation and the emerging therapeutic role of periodontal and dental pulp cell-derived small EVs (sEVs, <200 nm, or exosome). In this review, we discuss the biogenesis of three EV subtypes (sEVs, microvesicles and apoptotic bodies) and the emerging role of sEVs from periodontal ligament (stem) cells, gingival fibroblasts (or gingival mesenchymal stem cells) and dental pulp cells, and their therapeutic potential in vitro and in vivo. A review of the relevant methodology found that precipitation-based kits and ultracentrifugation are the two most common methods to isolate periodontal (dental pulp) cell sEVs. Periodontal (and pulp) cell sEVs range in size, from 40 nm to 2 μm, due to a lack of standardized isolation protocols. Nevertheless, our review found that these EVs possess anti-inflammatory, osteo/odontogenic, angiogenic and immunomodulatory functions in vitro and in vivo, via reported EV cargos of EV–miRNAs, EV–circRNAs, EV–mRNAs and EV–lncRNAs. This review highlights the considerable therapeutic potential of periodontal and dental pulp cell-derived sEVs in various regenerative applications.