Navegando por Palavras-chave "Osteoblast"
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- ItemSomente MetadadadosCalcium phosphate fibers coated with collagen: in vivo evaluation of the effects on bone repair(Cadernos Saude Publica, 2016) Ueno, Fabio Roberto [UNIFESP]; Kido, Hueliton Wilian [UNIFESP]; Granito, Renata Neves [UNIFESP]; Gabbai-Armelin, Paulo Roberto [UNIFESP]; Magri, Angela Maria Paiva [UNIFESP]; Fernandes, Kelly Rossetti [UNIFESP]; Silva, Antonio Carlos da; Braga, Francisco José Correa; Renno, Ana Claudia Muniz [UNIFESP]The aim of this study was to assess the characteristics of the CaP/Col composites, in powder and fiber form, via scanning electron microscopy (SEM), pH and calcium release evaluation after immersion in SBF and to evaluate the performance of these materials on the bone repair process in a tibial bone defect model. For this, four different formulations (CaP powder -CaPp, CaP powder with collagen -CaPp/Col, CaP fibers - CaPf and CaP fibers with collagen - CaPf/Col) were developed. SEM images indicated that both material forms were successfully coated with collagen and that CaPp and CaPf presented HCA precursor crystals on their surface. Although presenting different forms, FTIR analysis indicated that CaPp and CaPf maintained the characteristic peaks for this class of material. Additionally, the calcium assay study demonstrated a higher Ca uptake for CaPp compared to CaPf for up to 5 days. Furthermore, pH measurements revealed that the collagen coating prevented the acidification of the medium, leading to higher pH values for CaPp/Col and CaPf/Col. The histological analysis showed that CaPf/Col demonstrated a higher amount of newly formed bone in the region of the defect and a reduced presence of material. In summary, the results indicated that the fibrous CaP enriched with the organic part (collagen) glassy scaffold presented good degradability and bone-forming properties and also supported Runx2 and RANKL expression. These results show that the present CaP/Col fibrous composite may be used as a bone graft for inducing bone repair.
- ItemSomente MetadadadosEffects of high glucose and high insulin concentrations on osteoblast function in vitro(Springer, 2014-10-01) Cunha, Juliana S. [UNIFESP]; Ferreira, Vanessa M. [UNIFESP]; Maquigussa, Edgar [UNIFESP]; Naves, Marcelo A. [UNIFESP]; Boim, Mirian A. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Bone disease as a consequence of diabetes mellitus (DM) is not fully understood. the effects of high glucose (30 mM), high insulin (50 nM), or mannitol (30 mM; osmotic control) were evaluated on MC3T3-E1 cells (osteoblasts) in vitro. the mRNA and protein levels of parathyroid hormone (PTH) receptor (PTH1R), collagen I, RANKL, osteoprotegerin (OPG), alkaline phosphatase (ALP), and glucose transporter (GLUT1) were estimated by real-time polymerase chain reaction or Western blotting. the mineralization capacity was analyzed by von Kossa staining. High glucose induced overexpression of RANKL (2x) and OPG (30x), suggesting that RANKL-induced osteoclast activity might not be a dominant mechanism of bone disease in DM, since this increase was followed by increased OPG. Collagen I increased by 12x, indicating an excess of organic matrix production. the expression of ALP decreased by 50 %, indicating a deficit in mineralization capacity, confirmed by von Kossa staining. Mannitol induced similar effects as glucose suggesting that extracellular hyperosmolarity was able to stimulate organic matrix production. GLUT1 expression was not altered, and insulin did not reverse most of the effects of glucose, suggesting that glucose uptake by osteoblasts was not altered by high glucose. the data suggest that the bone fragility typical of DM is not a consequence of excessive bone reabsorption but is instead attributable to a defect in organic matrix mineralization. the heightened increase in OPG versus RANKL might cause a decrease in the bone-remodeling cycle. Osteoblasts appear to be more sensitive to extracellular hypertonicity than to the intracellular metabolic effects of hyperglycemia.
- ItemSomente MetadadadosGenetic Analysis of Lrp5 Function in Osteoblast Progenitors(Springer, 2010-05-01) Yadav, Vijay K.; Arantes, Henrique Pierotti [UNIFESP]; Barros, Elizabete Ribeiro [UNIFESP]; Lazaretti-Castro, Marise [UNIFESP]; Ducy, Patricia; Columbia Univ; Universidade Federal de São Paulo (UNIFESP)The low-density lipoprotein receptor-related protein (Lrp)-5 regulates osteoblast proliferation and bone formation through its expression in duodenum by modifying the gut serotonin-bone endocrine axis. However, its direct role, if any, in osteoblast progenitor cells has not been studied thus far. Here, we show that mice with a Dermo1-Cre-mediated disruption of Lrp5 in osteoblast progenitor cells have normal embryonic skeletogenesis and normal skeletal growth and development postnatally. Histomorphometric analysis of 3-month-old adult mice revealed normal osteoblast numbers, bone formation rate, and bone mass in Lrp5 (Dermo) (-/-) mice. in addition, analysis of two osteoporosis pseudoglioma (OPPG) patients revealed a three- to fivefold increase in their serum serotonin levels compared to age-matched controls. These results rule out a direct function of Lrp5 in osteoblast progenitor cells and add further support to the notion that dysregulation of serotonin synthesis is involved in bone mass abnormalities observed in OPPG patients.
- ItemSomente MetadadadosIntermittent PTH1-34 Causes DNA and Chromosome Breaks in Osteoblastic and Nonosteoblastic Cells(Springer, 2010-11-01) Alves de Oliveira, Elisangela Claudia [UNIFESP]; Szejnfeld, Vera Lucia [UNIFESP]; Silva, Neusa Pereira da [UNIFESP]; Coelho Andrade, Luis Eduardo [UNIFESP]; Moura Castro, Charlles Heldan de [UNIFESP]; Disciplina Reumatol; Universidade Federal de São Paulo (UNIFESP)Toxicological studies have demonstrated that intermittent PTH1-34 treatment is associated with an increased incidence of osteosarcoma in Fischer 344 rats. Comet and micronucleus (MN) tests, standard methods to evaluate genotoxic potential of drugs, were used to detect DNA and chromosome breaks, respectively, after PTH1-34 treatment. MC3T3 cells, primary osteoblast calvarial cells, and human osteoblasts were treated with PTH1-34 (50 and 100 nM) for 6 h/day for 21 days to mimic intermittent administration. Genotoxic assays were performed at 6 h and 7, 14, and 21 days. Osteoblasts extracted from bone marrow of mice treated with daily subcutaneous PTH1-34 injections (20 and 40 mu g/kg) for 10 weeks as well as Hep-2, HeLa, and Hep-G2 cells were also tested. We observed a significant increase in DNA lesions and MN prevalence in human and murine osteoblasts treated with PTH1-34 compared to controls (P < 0.01). the effect observed in vitro and confirmed in vivo was time- and dose-dependent. for nonosteoblastic Hep-2 and HeLa cells we observed increased DNA damage and MN prevalence only later in the course of the protocol, after 21 days of treatment (P < 0.01). in Hep-G2 cells intermittent PTH1-34 did not induce DNA damage or chromosome breaks. Our results demonstrated that intermittent PTH increases DNA and chromosome breaks in osteoblasts. This genotoxic effect is attenuated in nonosteoblastic cells, and the ability to induce DNA damage is lost in cells with detoxification properties (HepG2 cells) tested in vitro.
- ItemSomente MetadadadosRiboflavin and photoproducts in MC3T3-E1 differentiation(Elsevier B.V., 2010-10-01) Chaves Neto, Antonio Hernandes; Yano, Claudia Lumy; Paredes-Gamero, Edgar Julian [UNIFESP]; Machado, Daisy; Justo, Giselle Zenker [UNIFESP]; Peppelenbosch, Maikel P.; Ferreira, Carmen Verissima; Universidade Estadual de Campinas (UNICAMP); Universidade Federal de São Paulo (UNIFESP); Univ GroningenPhotoderivatives of riboflavin can modulate the proliferation and survival of cancer cells. in this work, we examined the influence of riboflavin and photoderivatives on osteoblast differentiation induced by ascorbic acid and beta-glycerophosphate. These compounds decreased the osteoblast proliferation, increased the alkaline phosphatase activity, promoted a reduction in matrix metalloproteinase-2 activity and the decreased in the OPG/RANKL ratio. the effects of flavins on osteoblasts were unrelated to the antioxidant activity of these compounds. the biological activity of osteogenic medium containing riboflavin and its photoderivatives involved the activation of different signaling pathways (AKT, FAK, CaMKII), caspases-3, -8 and -9, and up-regulation of the expression and/or stabilization of osteoblastic transcription factors (Runx2 and beta-catenin). These findings suggest a potential use of flavins as adjuvants to improve bone metabolism. (C) 2010 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosSerum from children with polyarticular juvenile idiopathic arthritis (pJIA) inhibits differentiation, mineralization and may increase apoptosis of human osteoblasts in vitro(Springer, 2009-01-01) Caparbo, Valeria F.; Prada, Flavia; Silva, Clovis A. A.; Regio, Paula L.; Pereira, Rosa M. R.; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)We examined the effects of polyarticular juvenile idiopathic arthritis (pJIA) serum on proliferation, differentiation, mineralization, and apoptosis of human osteoblast cells (hOb) in culture. the hOb were cultured with 10% serum from active pJIA and healthy controls (CT) and were tested for DNA synthesis, alkaline phosphatase (AP) activity, osteocalcin (OC) secretion, calcium levels, caspase 3 activity, and DNA fragmentation. None of the patients had used glucocorticoids for at least 1 month before the study, or any other drug that can affect bone mineral metabolism. Human inflammatory cytokine levels (IL-6, IL-8, IL-10, IL-1 beta, TNF-alpha, and IL-12p70) were measured in pJIA and CT sera. Low levels of AP activity was observed in pJIA cultures compared with CT cultures (67.16 +/- 53.35 vs 100.11 +/- 50.64 mu mol p-nitrophenol/h(-1) mg(-1) protein, P=0.008). There was also a significant decrease in OC secretion (9.23 +/- 5.63 vs 12.82 +/- 7.02 ng/mg protein, P=0.012) and calcium levels (0.475 +/- 0.197 vs 0.717 +/- 0.366 mmol/l, P=0.05) in pJIA hOb cultures. No difference was observed in cell proliferation (323.56 +/- 108.23 vs 328.91 +/- 88.03 dpm/mg protein, P=0.788). Osteoblasts cultured with JIA sera showed lower levels of DNA and increased fragmentation than osteoblasts cultured with CT sera. pJIA sera showed higher IL-6 values than CT (21.44 +/- 9.31 vs 3.58 +/- 2.38 pg/ml, P<0.001), but no difference was observed related to IL-8, IL-10, IL-1 beta, TNF-alpha, and IL-12p70 between pJIA and controls. This study suggests that serum from children with pJIA inhibits differentiation, mineralization and may increase apoptosis of hOb cultures, and inflammatory cytokines such as IL-6 might be a mechanism in this find. These results may represent an alternative therapeutic target for prevention and treatment of bone loss in JIA.
- ItemAcesso aberto (Open Access)Specification of osteoblast cell fate by canonical Wnt signaling requires Bmp2(Company Of Biologists Ltd, 2016) Salazar, Valerie S.; Ohte, Satoshi; Capelo, Luciane Portas [UNIFESP]; Gamer, Laura; Rosen, VickiEnhanced BMP or canonical Wnt (cWnt) signaling are therapeutic strategies employed to enhance bone formation and fracture repair, but the mechanisms each pathway utilizes to specify cell fate of bone-forming osteoblasts remain poorly understood. Among all BMPs expressed in bone, we find that singular deficiency of Bmp2 blocks the ability of cWnt signaling to specify osteoblasts from limb bud or bone marrow progenitors. When exposed to cWnts, Bmp2-deficient cells fail to progress through the Runx2/Osx1 checkpoint and thus do not upregulate multiple genes controlling mineral metabolism in osteoblasts. Cells lacking Bmp2 after induction of Osx1 differentiate normally in response to cWnts, suggesting that pre-Osx1(+) osteoprogenitors are an essential source and a target of BMP2. Our analysis furthermore reveals Grainyhead-like 3 (Grhl3) as a transcription factor in the osteoblast gene regulatory network induced during bone development and bone repair, which acts upstream of Osx1 in a BMP2-dependent manner. The Runx2/Osx1 transition therefore receives crucial regulatory inputs from BMP2 that are not compensated for by cWnt signaling, and this is mediated at least in part by induction and activation of Grhl3.