Cytotoxic Effects of Zoledronic Acid on Human Epithelial Cells and Gingival Fibroblasts

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dose-Response and Time-Course of a-Tocoferol Mediating the Cytoprotection Of Dental Pulp Cells Against Hydrogen Peroxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diabetes reduces mesenchymal stem cells in fracture healing through a TNF alpha-mediated mechanism

Diabetes interferes with bone formation and impairs fracture healing, an important complication in humans and animal models. The aim of this study was to examine the impact of diabetes on mesenchymal stem cells (MSCs) during fracture repair.Fracture of the long bones was induced in a streptozotocin-induced type 1 diabetic mouse model with or without insulin or a specific TNF alpha inhibitor, pegsunercept. MSCs were detected with cluster designation-271 (also known as p75 neurotrophin receptor) or stem cell antigen-1 (Sca-1) antibodies in areas of new endochondral bone formation in the calluses. MSC apoptosis was measured by TUNEL assay and proliferation was measured by Ki67 antibody. In vitro apoptosis and proliferation were examined in C3H10T1/2 and human-bone-marrow-derived MSCs following transfection with FOXO1 small interfering (si)RNA.Diabetes significantly increased TNF alpha levels and reduced MSC numbers in new bone area. MSC numbers were restored to normal levels with insulin or pegsunercept treatment. Inhibition of TNF alpha significantly reduced MSC loss by increasing MSC proliferation and decreasing MSC apoptosis in diabetic animals, but had no effect on MSCs in normoglycaemic animals. In vitro experiments established that TNF alpha alone was sufficient to induce apoptosis and inhibit proliferation of MSCs. Furthermore, silencing forkhead box protein O1 (FOXO1) prevented TNF alpha-induced MSC apoptosis and reduced proliferation by regulating apoptotic and cell cycle genes.Diabetes-enhanced TNF alpha significantly reduced MSC numbers in new bone areas during fracture healing. Mechanistically, diabetes-enhanced TNF alpha reduced MSC proliferation and increased MSC apoptosis. Reducing the activity of TNF alpha in vivo may help to preserve endogenous MSCs and maximise regenerative potential in diabetic patients.

Responses of Dental Pulp Cells to a Less Invasive Bleaching Technique Applied to Adhesively Restored Teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxic and genotoxic effects of ethanolic extract of Euphorbia hyssoptfolia L. on HepG2 cells

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Human ABCB1 confers cells resistance to cytotoxic guanidine alkaloids from Pterogyne nitens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biotransformed soybean extract induces cell death of estrogen-dependent breast cancer cells by modulation of apoptotic proteins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxic and genotoxic effects of high concentrations of the immunosuppressive drugs cyclosporine and tacrolimus in MRC-5 cells

Immunosuppressive drugs are used to suppress immune system activity in transplant patients and reduce the risk of organ rejection. The present study evaluated the potential cytotoxic, genotoxic and mutagenic of the immunosuppressive drugs cyclosporine (CsA) and tacrolimus (FK-506) on normal human fibroblasts (MRC-5 cells). Based on plasma concentrations of the immunosuppressive drugs, which were obtained from the records of kidney transplant patients at the Kidney Institute of Londrina, Brazil, 11 concentrations of each immunosuppressive were chosen to evaluate cell viability using the MIT assay. From these results, CsA and FK-506 concentrations of 135, 300, 675, and 1520 ng/ml and 8, 16, 24, and 32 ng/ml, respectively, were evaluated using (i) the comet assay, (ii) the nuclear division index (NDI), (iii) the micronucleus test (CBMN) and (iv) cell proliferation curves generated by quantifying cell numbers and protein levels. In this study, 1520 to 3420 ng/ml CsA decreased cell viability after 48 h of exposure. Genotoxic effects were observed only with a concentration of 1520 ng/ml after 3 h of exposure and with concentrations of 675 and 1520 ng/ml after 24 h of exposure. Mutagenic effects were observed only for the concentration of 1520 ng/ml. FK-506 decreased cell viability after 72 h of exposure for concentrations up to 20 ng/ml; genotoxic effects were observed with concentrations up to 8 ng/ml for both treatment times (3 and 24 h) and mutagenic effects were observed with concentrations of 24 and 32 ng/ml after 24 h of treatment. The cell proliferation curves demonstrated the absence of cytostatic effects of these drugs, and these data were confirmed by the NDI analysis. Our results suggest that concentrations lower than 300 ng/ml of CsA and 16 ng/ml of FK-506 are safe for use, as they did not induce genotoxic and mutagenic damage or affect MRC-5 cell viability and proliferation. (C) 2014 Elsevier GmbH. All rights reserved.

Studies of natural killer cells in patients with paracoccidioidomycosis

The number and activity of natural killer (NK) cells were studied in 34 untreated patients with paracoccidioidomycosis, 20 with the chronic form of the disease and 14 with the acute form. NK cells were detected with monoclonal antibody Leu-11c and the cytotoxic activity was measured using a single cell assay against K562 target cells. Both groups of patients had an increased number of circulating NK cells, their cytotoxic activity being significantly lower than in the healthy controls. These findings may be of importance in the immunological disturbances associated with paracoccidioidomycosis since NK cells exert important immune effector functions and may play a role in resistance against Paracoccidioides brasiliensis.

Transdentinal cytotoxicity of glutaraldehyde on odontoblast-like cells

This study investigated the transdentinal cytotoxicity of glutahaldehyde-containing solutions/materials on odontoblast-like cells. Dentin discs were adapted to artificial pulp chambers. MDPC-23 cells were seeded on the pulpal side of the discs and the occlusal surface was treated with the following solutions: water, 2% glutaraldehyde (GA), 5% GA, 10% GA, Gluma Comfort Bond+Desensitizer (GCB+De) or Gluma Desensitizer (GDe). Cell viability and morphology were assessed by the Alamar Blue assay and SEM. The eluates were collected and applied on cells seeded in 24-well plates. After 7 or 14 days the total protein (TP) production, alkaline phosphatase activity (ALP) and deposition of mineralized nodules (MN) were evaluated. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (p<0.05). GA solutions were not cytotoxic against MDPC-23. GCB+De (85.1%) and GDe (77.2%) reduced cell viability as well as TP production and ALP activity at both periods. After 14 days, GCB+De and GDe groups produced less MN. Affected MDPC-23 presented deformation of the cytoskeleton and reduction of cellular projections. The treatment with 2.5%, 5% and 10% GA was not harmful to odontoblast-like cells. Conversely, when GA was combined with other components like HEMA, the final material became cytotoxic. Glutaraldehyde has been used to decrease dentin hypersensitivity. This substance is also capable of preventing resin-dentin bond degradation by cross-linking collagen and MMPs. This study showed that GA might be safe when applied on acid etched dentin. However, when combined with HEMA the product becomes cytotoxic.

Responses of human dental pulp cells after application of a low-concentration bleaching gel to enamel

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toxicogenetic effects of low concentrations of the pesticides imidacloprid and sulfentrazone individually and in combination in in vitro tests with HepG2 cells and Salmonella typhimurium

The insecticide imidacloprid and the herbicide sulfentrazone are two different classes of pesticides that are used for pest control in sugarcane agriculture. To evaluate the genotoxic potential of low concentrations of these two pesticides alone and in mixture, the comet assay and the micronucleus (MN) test employing fluorescence in situ hybridization (FISH) with a centromeric probe were applied in human hepatoma cell lines (HepG2), in a 24-h assay. Mutagenicity was assessed by Salmonella/microsome assay with TA98 and TA100 strains in the absence and presence of an exogenous metabolizing system (S9). The results showed significant inductions of MN in HepG2 cells by both pesticides, for all the tested concentrations. As evidenced in the comet assay, only the imidacloprid presented significant responses. When the two pesticides were associated, a significant induction of damage was observed in the HepG2 cells by the comet assay, but not by the MN test. Moreover, the MN induced by the mixtures of the pesticides appeared at lower levels than those induced by sulfentrazone and imidacloprid when tested alone. According to the FISH results, the damage induced by imidacloprid in the HepG2 cells resulted from a clastogenic action of this insecticide (76.6% of the MN did not present a centromeric signal). For the herbicide sulfentrazone and for the mixture of the pesticides, a similar frequency of MN with and without the presence of the centromeric signal (herbicide: 52.45% of the MN without centromeric signal and 47.54% of the MN with centromeric signal; mixture: 48.71% of the MN without centromeric signal and 51.42% of the MN with centromeric signal) was verified. Based on these results, it was concluded that each one of the pesticides evaluated interacts with the DNA of HepG2 cells and causes irreparable alterations in the cells. However, the combination of the pesticides showed an antagonistic effect on the cells and the damage induced was milder and not persistent in HepG2 cells. The results obtained by the Ames test did not point out significant results.

Metformin and soybean-derived bioactive molecules attenuate the expansion of stem cell-like epithelial subpopulation and confer apoptotic sensitivity in human colon cancer cells

Colorectal cancer (CRC) is a disease whose genesis may include metabolic dysregulation. Cancer stem cells are attractive targets for therapeutic interventions since their aberrant expansion may underlie tumor initiation, progression, and recurrence. To investigate the actions of metabolic regulators on cancer stem cell-like cells (CSC) in CRC, we determined the effects of soybean-derived bioactive molecules and the anti-diabetes drug metformin (MET), alone and together, on the growth, survival, and frequency of CSC in human HCT116 cells. Effects of MET (60 μM) and soybean components genistein (Gen, 2 μM), lunasin (Lun, 2 μM), β-conglycinin (β-con, 3 μM), and glycinin (Gly, 3 μM) on HCT116 cell proliferation, apoptosis, and mRNA/protein expression and on the frequency of the CSC CD133(+)CD44(+) subpopulation by colonosphere assay and fluorescence-activated cell sorting/flow cytometry were evaluated. MET, Gen, and Lun, individually and together, inhibited HCT116 viability and colonosphere formation and, conversely, enhanced HCT116 apoptosis. Reductions in frequency of the CSC CD133(+)CD44(+) subpopulation with MET, Gen, and Lun were found to be associated with increased PTEN and reduced FASN expression. In cells under a hyperinsulinemic state mimicking metabolic dysregulation and without and with added PTEN-specific inhibitor SF1670, colonosphere formation and frequency of the CD133(+)CD44(+) subpopulation were decreased by MET, Lun and Gen, alone and when combined. Moreover, MET + Lun + Gen co-treatment increased the pro-apoptotic and CD133(+)CD44(+)-inhibitory efficacy of 5-fluorouracil under hyperinsulinemic conditions. Results identify molecular networks shared by MET and bioavailable soy food components, which potentially may be harnessed to increase drug efficacy in diabetic and non-diabetic patients with CRC.

Analysis of the genotoxic potential of low concentrations of Malathion on the Allium cepa cells and rat hepatoma tissue culture

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transdentinal cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)