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Aims: Dental pulp stem cells (DPSCs) contain a population of stem cells with a broad range of differentiation potentials, as well as more lineage‐committed progenitors. Such heterogeneity is a significant obstacle to experimental and clinical applications. The aim of this study is to isolate and characterize a homogenous neuronal progenitor cell population from human DPSCs. Methodology: Polysialylated‐neural cell adhesion molecule (PSA‐NCAM+) neural progenitors were isolated from the dental pulp of three independent donors using magnetic‐activated cell sorting (MACS) technology. Immunofluorescent staining with a panel of neural and non‐neural markers was used to characterize the magnetically isolated PSA‐NCAM+ fraction. PSA‐NCAM+ cells were then cultured in Neurobasal A supplemented with neurotrophic factors: dibutyryl cyclic‐AMP, neurotrophin‐3, B27 and N2 supplements to induce neuronal differentiation. Both PSA‐NCAM+ and differentiated PSA‐NCAM+ cells were used in Ca2+ imaging studies to assess the functionality of P2X3 receptors as well as membrane depolarization. Results: PSA‐NCAM+ neural progenitors were isolated from a heterogeneous population of hDPSCs using magnetic‐activated cell sorting and anti‐PSA‐NCAM MicroBeads. Flow cytometry analysis demonstrated that immunomagnetic sorting significantly increased the purity of PSA‐NCAM+ cells. Immunofluorescent staining revealed expression of pan‐neuronal and mature neuronal markers, PGP9.5 and MAP2, respectively, as well as weak expression of the mature sensory markers, peripherin and islet1. ATP‐induced response was mediated predominately by P2X3 receptors in both undifferentiated and differentiated cells, with a greater magnitude observed in the latter. In addition, membrane depolarizations were also detected in cells before and after differentiation when loaded with fast‐voltage‐responding fluorescent molecule, FluoVolt™ in response to potassium chloride. Interestingly, only differentiated PSA‐NCAM+ cells were capable of spontaneous membrane oscillations. Conclusions: In summary, DPSCs contain a population of neuronal progenitors with enhanced neural differentiation and functional neural‐like properties that can be effectively isolated with magnetic‐activated cell sorting (MACS). [ABSTRACT FROM AUTHOR]

Aim: To evaluate the expression and function of the nod‐like receptor pyrin domain containing 3 (NLRP3) inflammasome in caries induced pulpitis. Methodology: NLRP3 expression was determined with immunohistochemistry in the dental pulp and qPCR in dental pulp cells (DPCs). THP‐1 macrophages expressing the apoptosis‐related speck‐like protein (ASC) and green fluorescent protein (GFP) fusion protein were used to assess NLRP3 inflammasome activation by live cell imaging, following treatment with lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Caspase I inhibitor was used to confirm inflammasome activation. An ex‐vivo pulpitis model in which the DPCs were co‐cultured with THP‐1 macrophages was used to study the effect of the NLRP3 inflammasome inhibitor (MCC950), and cytokines were measured using ELISA and multiplex array. Data were analysed using the t‐test or anova followed by a Bonferroni post hoc test with the level of significance set at p ≤.05. Results: NLRP3 inflammasome was differentially expressed in dental pulp of sound and carious teeth. Treatment of DPCs with LTA significantly upregulates NLRP3 and IL‐1 β‐expression (p <.05) and in induces more ASC specks formation compared to LPS. IL‐β release in response to LTA treatment is significantly reduced with Caspase I inhibitor suggesting inflammasome dependent mechanism (p <.01). NLRP3‐specific inhibitor, MCC950, significantly reduced IL‐1β and IL‐6 in an ex‐vivo pulpitis model (p <.01) but had no effect on IL‐8 or matrix metalloproteinase‐9 (MMP‐9). Conclusions: Expression and upregulation of NLRP3 inflammasome with caries and LTA treatment suggest a role in caries‐induced pulpitis. NLRP3 inhibitor attenuated the release of selective inflammatory cytokines and could be a potential treatment target that merit further investigation. [ABSTRACT FROM AUTHOR]

Aim: To create an irreversible pulpitis gene signature from microarray data of healthy and inflamed dental pulps, followed by a bioinformatics approach using connectivity mapping to identify therapeutic compounds that could potentially treat pulpitis. Methodology: The Gene Expression Omnibus (GEO) database, an international public repository of genomics data sets, was searched for human microarray datasets assessing pulpitis. An irreversible pulpitis gene expression signature was generated by differential expression analysis. The statistically significant connectivity map (ssCMap) method was used to identify compounds with a highly correlating gene expression pattern. qPCR was used to validate novel pulpitis genes. An ex vivo pulpitis model was used to test the effects of the compounds identified, and the level of inflammatory cytokines was measured with qPCR, ELISA and multiplex array. Means were compared using the t‐test or ANOVA with the level of significance set at p ≤.05. Results: Pulpitis gene signatures were created using differential gene expression analysis at cutoff points p =.0001 and.000018. Top upregulated genes were selected as potential pulpitis biomarkers. Among these, IL8, IL6 and MMP9 were previously identified as pulpitis biomarkers. Novel upregulated genes, chemokine (C‐C motif) ligand 21 (CCL21), metallothionein 1H (MT1H) and aquaporin 9 (AQP9) were validated in the pulp tissue of teeth clinically diagnosed with irreversible pulpitis using qPCR. ssCMap analysis identified fluvastatin (Statin) and dequalinium chloride (Quaternary ammonium) as compounds with the strongest correlation to the gene signatures (p =.0001). Fluvastatin reduced IL8, IL6, CCL21, AQP9 (p <.001) and MMP9 (p <.05) in the ex vivo pulpitis model, while dequalinium chloride reduced AQP9 (p <.001) but had no significant effect on the other biomarkers. Conclusions: AQP9, MT1H and CCL21 were identified and validated as novel biomarkers for pulpitis. Fluvastatin and dequalinium chloride identified by the ssCMap as potential therapeutics for pulpitis reduced selected pulpitis biomarkers in an ex vivo pulpitis model. In vivo testing of these licenced drugs is warranted. [ABSTRACT FROM AUTHOR]

Understanding dentinogenesis and pulp regeneration during physiological and pathological conditions represents a real challenge in the provision of a suitable treatment that ideally leads to the induction of the pulp regenerative potential. This paper focusses on the early steps of dentin-pulp regeneration that appear to be critical after pulp capping procedures. Different models are described in this paper where the interactions between different cell types in vitro illustrate their role in maintaining pulpal homeostasis. After traumatic injuries, the cells modify the local pulpal microenvironment by secreting growth factors that orchestrate and induce the processes required for dentin-pulp regeneration. Applying dental materials onto the injured pulp modifies this local microenvironment and affects the potential for pulpal regeneration. The paper also describes the added value of developing an entire human tooth culture model for understanding these early steps and discusses the interest of its use in evaluating newly developed pulp capping materials through the example of BiodentineTM, developed as a dentin substitute. The growth factors sustained release simulating the local microenvironment is also discussed. Simulating the pulp local environment with a continuous growth factors release is also a basic requirement for establishing future pulp tissue engineering. [ABSTRACT FROM AUTHOR]

In a previous work, based on an in vitro entire tooth culture model of human immature third molars, we demonstrated that perivascular progenitor cells can proliferate and migrate to the injury site after pulp exposure. In this work, we investigated the differentiation of cells after direct capping with biomaterials classically used in restorative dentistry. Histological staining after direct pulp capping with Calcium Hydroxide XR® or MTA revealed early and progressive mineralized foci formation containing BrdU‐labeled sequestered cells. The molecular characterization of the matrix and the sequestered cells by immunohistochemistry (Collagene type I, Dentin sialoprotein, and Nestin) clearly demonstrates that these areas share common characteristics of the mineralized matrix of reparative dentin formed by odontoblast‐like cells. This reproduces some features of the pulp responses after applying these materials in vivo and demonstrates that the entire tooth culture model reproduces a part of the early steps of dentin regeneration in vivo. Its future development may be useful in studying the effects of biomaterials on this process. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

The article offers information on oral biology professor Imad About. It states that About joined the University la Méditerranée as an assistant professor at the Faculty of Dentistry of Marseille in France in 1996. It mentions that his research group involves in investigating the role of progenitor and non-progenitor cells in the regeneration of dentin.