ascorbic-acid and hydroxyethyl-methacrylate

The aim of this study was to investigate the effects of HEMA and TEGDMA on the odontogenic differentiation potential of dental pulp stem/progenitor cells.. Dental stem/progenitor cell cultures were established from pulp biopsies of human deciduous teeth of 1-3 year-old children (Deciduous Teeth Stem Cells-DTSCs). Cultures were characterized for stem cell markers, including STRO-1, CD146, CD34, CD45 using flow cytometry. Cytotoxicity was evaluated with the MTT assay. DTSCs were then induced for osteo/odontogenic differentiation by media containing dexamethasone, KH(2)PO(4),β-glycerophosphate and L-ascorbic acid phosphate in the presence of nontoxic concentrations of HEMA (0.05-0.5mM) and TEGDMA (0.05-0.25mM) for 3 weeks. Additionally, the effects of a single exposure (72 h) to higher concentrations of HEMA (2mM) and TEGDMA (1mM) were also evaluated.. DTSCs cultures were positive for STRO-1 (7.53±2.5%), CD146 (91.79±5.41%), CD34 (11.87±3.02%) and negative for CD45. In the absence of monomers cell migration, differentiation and production of mineralized dentin-like structures could be observed. Cells also progressively expressed differentiation markers, including dentin sialophosphoprotein-DSPP, bone sialoprotein-BSP, osteocalcin-OCN and alkaline phosphatase-ALP. On the contrary, long-term exposure to nontoxic concentrations of HEMA and TEGDMA significantly delayed the differentiation and mineralization processes of DTSCs, whereas, one time exposure to higher concentrations of these monomers almost completed inhibited mineral nodule formation. BSP, OCN, ALP and DSPP expression were also significantly down-regulated.. These findings suggest that HEMA and TEGDMA can severely disturb the odontogenic differentiation potential of pulp stem/progenitor cells, which might have significant consequences for pulp tissue homeostasis and repair.

Topics: Alkaline Phosphatase; Antigens, CD34; Antigens, Surface; Ascorbic Acid; Biomarkers; Calcification, Physiologic; CD146 Antigen; Cell Differentiation; Cell Movement; Cells, Cultured; Child, Preschool; Dental Pulp; Dexamethasone; Down-Regulation; Extracellular Matrix Proteins; Glucocorticoids; Glycerophosphates; Humans; Infant; Integrin-Binding Sialoprotein; Leukocyte Common Antigens; Methacrylates; Odontogenesis; Osteocalcin; Phosphates; Phosphoproteins; Polyethylene Glycols; Polymethacrylic Acids; Potassium Compounds; Sialoglycoproteins; Stem Cells; Tooth, Deciduous

Cytotoxic methacrylate monomers have been identified in aqueous extracts of freshly cured compomers. Some of these compounds, including HEMA and TEGDMA, induce apoptosis and necrosis in vitro. The aim of the present study was to elucidate possible signaling pathways involved in apoptosis following exposure to HEMA or TEGDMA in a salivary gland cell line.. The cells were exposed to various concentrations of HEMA or TEGDMA. ROS formation was determined by dichlorofluorescein assay. Phosphorylated MAP-kinases ERK1/2, p38 and JNK, as well as specific caspases were identified by Western blotting. Apoptosis was assayed by fluorescence microscopy.. HEMA or TEGDMA exposure resulted in ROS formation and concentration-dependent apoptosis as well as phosphorylation of ERK. Phosphorylation of JNK and p38 was induced by HEMA. Selective inhibitors of ERK and JNK modified the apoptotic response after HEMA and TEGDMA exposure, whereas p38 inhibition modified the apoptotic response only after HEMA exposure. Vitamin C reduced HEMA-induced apoptosis.. ROS formation and differential MAP kinase activation appear to be involved in the apoptotic response following exposure to HEMA and TEGDMA.

Topics: Animals; Antioxidants; Apoptosis; Ascorbic Acid; Blotting, Western; Caspases; Cell Line; Dental Materials; Enzyme Activation; Flavonoids; Fluorescent Dyes; MAP Kinase Kinase 4; Methacrylates; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Polyethylene Glycols; Polymethacrylic Acids; Rats; Reactive Oxygen Species; Signal Transduction; Time Factors

Resin-based materials are now widely used in dental restorations. Although the use of these materials is aesthetically appealing to patients, it carries the risk of local and systemic adverse effects. The potential risks are direct damage to the cells and induction of immune-based hypersensitivity reactions. Dental pulp stromal cells (DPSCs) and oral keratinocytes are the major cell types which may come in contact with dental resins such as 2-hydroxyethyl methacrylate (HEMA) after dental restorations. Here we show that N-acetylcysteine (NAC) inhibits HEMA-induced apoptotic cell death and restores the function of DPSCs and oral epithelial cells. NAC inhibits HEMA-mediated toxicity through induction of differentiation in DPSCs, because the genes for dentin sialoprotein, osteopontin (OPN), osteocalcin, and alkaline phosphatase, which are induced during differentiation, are also induced by NAC. Unlike NAC, vitamins E and C, which are known antioxidant compounds, failed to prevent either HEMA-mediated cell death or the decrease in VEGF secretion by human DPSCs. More importantly, when added either alone or in combination with HEMA, vitamin E and vitamin C did not increase the gene expression for OPN, and in addition vitamin E inhibited the protective effect of NAC on DPSCs. NAC inhibited the HEMA-mediated decrease in NF-kappaB activity, thus providing a survival mechanism for the cells. Overall, the studies reported in this paper indicate that undifferentiated DPSCs have exquisite sensitivity to HEMA-induced cell death, and their differentiation in response to NAC resulted in an increased NF-kappaB activity, which might have provided the basis for their increased protection from HEMA-mediated functional loss and cell death.

Topics: Acetylcysteine; Alkaline Phosphatase; Apoptosis; Ascorbic Acid; Cell Differentiation; Cell Proliferation; Cytoprotection; Dental Pulp; Free Radical Scavengers; Gene Expression; Humans; Methacrylates; NF-kappa B; Stromal Cells; Vascular Endothelial Growth Factor A; Vitamin E

The pharmacological action of vitamin E on the mechanical activity of isolated guinea pig colonic smooth muscle was examined in normoxic and hypoxic conditions. In hypoxia, but not normoxia, alpha-tocopherol (1-160 microM) evoked rapid concentration-dependent contractions from the colon. This was also seen with other members of the vitamin E family, and potency measurements gave EC(50) values (microM) of 10.6 +/- 0.9 for D-alpha-tocopherol, 6.0 +/- 1.2 for D-beta-tocopherol, 7.5 +/- 0.7 for D-gamma-tocopherol, and 6.1 +/- 1.5 for D-delta-tocopherol. This order of potency for the components of the vitamin differs from previously studied bioassay systems and from their antioxidant activity. A range of potent natural and synthetic antioxidants was not active in this system. Compounds with structural similarities to the side chain of vitamin E produced similar stimulatory responses and some, like phytol, were more potent than the vitamin (EC(50): 1.0 +/- 0.2 microM), whereas ring structures related to the vitamin, like Trolox C, antagonized the stimulant responses in a concentration-dependent manner. Therefore, this model system measures, directly, vitamin E-induced responses through a mechanism that does not appear to be related to the known antioxidant capacity of these agents.

Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; Chromans; Colon, Transverse; Dose-Response Relationship, Drug; Female; Guinea Pigs; Hypoxia; In Vitro Techniques; Isometric Contraction; Male; Methacrylates; Muscle Contraction; Muscle, Smooth; Phytol; Pyrogallol; Quantitative Structure-Activity Relationship; Stereoisomerism; Temperature; Terpenes

In a previous study it was postulated that toxicity of 2-hydroxyethylmethacrylate (HEMA) and triethleneglycoldimethacrylate (TEGDMA) is based on oxidative metabolites. In this study the influence of antioxidative vitamins (including uric acid) on the toxicity of HEMA or TEGDMA was tested. Toxicity of HEMA and TEGDMA was determined in rat alveolar epithelial L2, human malignant A549, and human fibroblast-like 11Lu cells by inhibition of methionine incorporation (as a marker of protein synthesis inhibition) and by determination of glutathione depletion, as well as by measurement of GSSG increase.. Toxicity of the composite components HEMA and TEGDMA was demonstrated by GSH depletion as the most sensitive method. Five hundred micromoles per litre Vitamin C or 250 micromol/l Vitamin E were mostly able to decrease toxicity of HEMA and TEGDMA in the cell lines tested. In addition, 250 micromol/l Vitamin A was only effective in L2 cells impairing HEMA toxicity and 250 micromol/l uric acid impairing TEGDMA toxicity as assessed by decreased GSH depletion. In A549 cells only methionine incorporation inhibition but not GSH depletion was significantly affected. By contrast, in 11Lu cells methionine incorporation inhibition was not significantly changed, but GSH depletion was.. The postulated mechanism of HEMA or TEGDMA toxicity based on radical metabolites is supported by the effectivity of the antioxidative substances tested in mitigating toxicity and by the greater susceptibility of the glutathione redox system as compared to protein synthesis inhibition in assessing toxicity.

Topics: Animals; Antioxidants; Ascorbic Acid; Biocompatible Materials; Cell Line; Composite Resins; Glutathione; Glutathione Disulfide; Glutathione Reductase; Humans; Methacrylates; Methionine; NADH, NADPH Oxidoreductases; Polyethylene Glycols; Polymethacrylic Acids; Rats; Thioredoxin-Disulfide Reductase; Uric Acid; Vitamin E; Vitamins