Dental pulp inflammatory/immune response to a chitosan-enriched fibrin hydrogel in the pulpotomised rat incisor

Current pulpotomy is limited in its ability to induce regeneration of the dental-pulp (DP) complex. Hydrogels are reported to be well-suited for tissue engineering and are unlikely to induce an inflammatory response that might damage the remaining tissue. The present study investigated the molecular and cellular actors in the early inflammatory/immune response and deciphered M1/M2 macrophage polarisation to a chitosan-enriched fibrin hydrogel in pulpotomised rat incisors. Both fibrin and fibrin-chitosan hydrogels induced a strong increase in interleukin-6 (IL-6) transcript in the DP when compared to the DP of untreated teeth. Gene expression of other inflammatory mediators was not significantly modified after 3 h. In the viable DP cell population, the percentage of leukocytes assessed by flow cytometry was similar to fibrin and fibrin-chitosan hydrogels after 1 d. In this leukocyte population, the proportion of granulocytes increased beneath both hydrogels whereas the antigen-presenting cell, myeloid dendritic cells, T cells and B cells decreased. The natural killer (NK) cell population was significantly decreased only in DPs from teeth treated with fibrin-chitosan hydrogel. Immunolabeling analysis of the DP/hydrogel interface showed accumulation of neutrophil granulocytes in contact with both hydrogels 1 d after treatment. The DP close to this granulocyte area contained M2 but no M1 macrophages. These data collectively demonstrated that fibrin-chitosan hydrogels induced an inflammatory/immune response similar to that of the fibrin hydrogel. The results confirmed the potential clinical use of fibrin-chitosan hydrogel as a new scaffold for vital-pulp therapies

Gene-enhanced tissue engineering for dental hard tissue regeneration: (2) dentin-pulp and periodontal regeneration

Potential applications for gene-based tissue engineering therapies in the oral and maxillofacial complex include the delivery of growth factors for periodontal regeneration, pulp capping/dentin regeneration, and bone grafting of large osseous defects in dental and craniofacial reconstruction. Part 1 reviewed the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. This manuscript will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration

Psychometric validation of the French version of the Connor-Davidson Resilience Scale

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Immune Cells and Molecular Networks in Experimentally Induced Pulpitis

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Inorganic phosphate stimulates apoptosis in murine MO6-G3 odontoblast-like cells

International audienceObjective: Dental pathologies such as caries are the most prevalent disease worldwide with infectious and social complications. During the process of caries formation, the tooth is degraded and demineralization of enamel and dentine leads to the release of large amounts of inorganic phosphate (Pi) within dental tubuli. As Pi has been shown to induce apoptosis in skeletal cells, including osteoblasts and chondrocytes, we questioned whether high concentrations of Pi could affect odontoblast viability, proliferation and apoptosis.Design: Using the odontoblast-like MO6-G3 cell line as a model, we used cell counting and MTS-based colorimetric assays to measure cell viability and proliferation. Apoptosis was assessed using Hoechst nuclei staining and detection of the early apoptotic markers annexin V and Apo2.7.Results: We show for the first time that a high Pi concentration (7 mM) induced a decrease in odontoblast viability and proliferation together with a large increase in apoptosis. These effects were blunted in calcium-free medium, possibly due to the formation of calciumphosphate crystals in the presence of high Pi concentrations.Conclusion: This study contributes to clarifying the effect of Pi on odontoblast viability and apoptosis, which may improve our understanding of the role of Pi during caries formation

Tolerogenic dendritic cells actively inhibit T cells through heme oxygenase-1 in rodents and in nonhuman primates

International audienceClinical translation of dendritic cell (DC)-based cell therapy requires preclinical studies in nonhuman primates (NHPs). The aim of this work was to establish the in vitro conditions for generation of NHP tolerogenic DCs (Tol-DCs), as well as to analyze the molecular mechanisms by which these cells could control an immune response. Two populations of NHP bone marrow-derived DCs (BMDCs) were obtained: adherent and nonadherent. Although both populations displayed a quite similar phenotype, they were very different functionally. We characterized the adherent BMDCs as Tol-DCs that were poor stimulators of T cells and actively inhibited T-cell proliferation, whereas the nonadherent population displayed immunogenic properties in vitro. Interestingly, the anti-inflammatory and immunosuppressive enzyme heme oxygenase-1 (HO-1) was up-regulated in Tol-DCs, compared to the immunogenic BMDCs. We demonstrated that HO-1 mediates the immunosuppressive properties of Tol-DCs in vitro (in NHPs and rats) and that HO-1 is involved in the in vivo tolerogenic effect of Tol-DCs in a rat model of allotransplantation. In conclusion, here we characterized the in vitro generation of NHP Tol-DCs. Furthermore, we showed for the first time that HO-1 plays a role in the active inhibition of T-cell responses by rat and NHP Tol-DCs

Human periodontal ligament fibroblasts stimulated by nanocrystalline hydroxyapatite paste or enamel matrix derivative. An in vitro assessment of PDL attachment, migration, and proliferation

Item does not contain fulltextWe determined the effects of soluble or coated nanocrystalline hydroxyapatite paste (nano-HA) and enamel matrix derivative (EMD) on proliferation, adhesion, and migration of periodontal ligament fibroblasts (PDLs). Cultured PDLs were stimulated with nano-HA paste or EMD in a soluble form or were coated to the surface of cell culture dishes. Proliferation of PDLs on coated nano-HA and EMD was quantified by various methods including bromodeoxyuridine (BrdU) incorporation and Western blot. Cell migration was investigated in a modified Boyden chamber. The surface integrin profile of PDLs was determined using an integrin-specific ELISA, and integrin-specific signaling was measured by immunoblotting of phosphorylated focal adhesion kinase (FAK). Coated nano-HA stimulated PDL proliferation to a larger extent as compared with coated EMD. PDL migration towards a nano-HA or EMD gradient was more efficiently mediated by soluble EMD as compared with nano-HA but vice versa, adhesion of PDLs to compound-coated dishes was more effectively mediated by nano-HA as compared with EMD. Mechanistically, majorly integrin alpha5beta1-mediated adhesion of PDL and both coated compounds mediated a significant increase in FAK activation though to a different extent. Current findings offer two different modes of action for EMD and nano-HA paste. EMD efficiently acts as a chemoattractant in its soluble form, while nano-HA paste effectively serves as a synthetic extracellular matrix component in its coated form. Our findings suggest that EMD and nano-HA paste display different molecular characteristics and apply alternative routes to mediate their beneficial effects on periodontal tissues