Molecular aspects of the effect of transforming growth factor-beta 1 (TGF-β1) in the signaling pathways in vitro biomineralization.

Este estudo in vitro teve como objetivo avaliar os efeitos moleculares do TGF-β1, com diferentes períodos de suplementação, sobre a formação do fenótipo osteogênico das células MC3T3-E1, comparando-os com células tratadas com AA+β-GP suplementados com Dex e/ou TGF-β1, sem e com a neutralização dos receptores de TGF-β1. A expressão gênica do próprio TGF-β1 e Smad3 foram analisadas, bem como, a diferenciação das células osteogênicas e a biomineralização. As células tratadas com TGF-β1 sem neutralização de receptores apresentam efeito inibitório nos estágios mais avançados da diferenciação dos osteoblastos e da biomineralização in vitro, mas expressarem alguns marcadores importantes envolvidos na mineralização. Observaram-se nódulos de mineral em todos os tratamentos das células que tiveram os receptores de TGF-β1 neutralizados, mas houve uma diminuição na expressão de alguns genes. Os resultados confirmam a complexidade da via de sinalização do TGF-β1, mostrando que existem lacunas para que seja entendido o mecanismo dessa molécula na biologia osteoblástica.This in vitro study aimed to evaluate the molecular effects of TGF-β1, with different supplementation time periods on the establishment of MC3T3-E1 cells, comparing with cells treated with AA+β-GP supplemented with Dex and/or TGF-β1, without or with neutralization of TGF-β1 receptors. The gene expression of the TGF-β1 and Smad3 were analyzed, as well as the osteoblast differentiation and biomineralization. The cells treated with TGF-β1 without neutralization of receptors have had inhibitory effect on some important stages of osteoblast differentiation and biomineralization in vitro, but expressed some important mineralization markers. Mineral nodules were observed in all treatments of cells with their TGF-β1 receptors neutralized, but there was a decrease in the expression of some important genes. The results confirm the complexity of the pathway signaling of TGF-β1, showing that there are gaps for understand the mechanisms of this molecule in the biology of osteoblasts

Study of the influence of TGF-b1 in osteogenic cell culture induced by mineralizing factors.

O estudo investigou a influência do fator de transformação de crescimento beta1 (TGFb1) sobre células osteogênicas induzidas com fatores mineralizantes (dexametasona Dex), comparando a viabilidade e a proliferação celular, a mineralização, e a expressão de proteínas não colágenas da matriz osteopontina (OPN), sialoproteína óssea (BSP) e fibronectina (FN). A morfologia foi examinada por microscopia eletrônica de transmissão (MET). O TGFb1 diminuiu a viabilidade e a proliferação celular, mesmo com Dex. A mineralização da matriz foi positivo apenas no grupo tratado com Dex, e negativo nos grupos tratados TGFb1 e TGFb1+Dex. OPN e BSP não foram imunoreativas apenas para o controle negativo, já a FN foi imunoexpressa em todos os grupos. A mineralização foi confirmada, tanto no controle positivo quanto no tratado com Dex, e alterações morfológicas foram observadas nas células tratadas com TGFb1 e TGFb1+Dex, através da MET. Esse estudo mostrou que TGFb1 inibe a mineralização, alterando a viabilidade e proliferação, bem como a morfologia celular, mesmo quando tratadas com Dex.The study investigated the influence of transforming growth factor beta1 (TGFb1) on osteogenic cells induced with mineralizing factors (dexamethasone Dex), comparing the viability and proliferation cellular, the formation of mineral nodules in vitro, and the expression of the noncollagenous matrix proteins osteopontin (OPN), bone sialoprotein (BSP), and fibronectin (FN). The morphology was examined by transmission electron microscopy (TEM). The TGFb1 decreased the viability and proliferation cellular, even when combined with Dex. The mineralization of matrix was positive only in the group treated with Dex, and negative in the groups treated with TGFb1 and TGFb1+Dex. OPN and BSP were not immunoreactive only negative, already the FN was immunoreactive in all groups.The mineralizing was confirmed in the positive control and Dex, through TEM. Some morphological changes were seen in cells treated with TGFb1 and TGFb1+Dex. This study showed that TGFb1 inhibits the mineralization, changing the viability, proliferation and cell morphology, even when treated with Dex

In Vitro Cytotoxicity of a Ti-35Nb-7Zr-5Ta Alloy Doped with Different Oxygen Contents

Cp-Ti is the most common material used for dental implants, but its elastic modulus is around five times higher than that of bone. Recently, promising alloys that add Nb, Ta, Zr and Mo to Ti have been developed. The mechanical properties of these alloys are directly related to its microstructure and the presence of interstitial elements, such as oxygen, carbon, nitrogen and hydrogen. In this study, the in vitro cytotoxicity of Ti-35Nb-7Zr-5Ta (TNZT) alloys was analyzed in the as-received condition and after being doped with several small quantities of oxygen on a cultured osteogenic cell. The cell's morphology was also examined by scanning electron microscopy (SEM). The TNZT alloy presented no cytotoxic effects on osteoblastic cells in the studied conditions.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

A New α + β Ti-15Nb Alloy with Low Elastic Modulus: Characterization and In Vitro Evaluation on Osteogenic Phenotype

This study aimed to produce Ti-15Nb alloy with a low elastic modulus, verify its biocompatibility, and determine whether the alloy indirectly influences cellular viability and morphology, as well as the development of the osteogenic phenotype in cells cultured for 2, 3, and 7 days derived from rat calvarias. Two heat treatments were performed to modify the mechanical properties of the alloy where the Ti-15Nb alloy was heated to 1000 °C followed by slow (−5 °C/min) (SC) and rapid cooling (RC). The results of structural and microstructural characterization (XRD and optical images) showed that the Ti-15Nb alloy was of the α + β type, with slow cooling promoting the formation of the α phase and rapid cooling the formation of the β phase, altering the values for the hardness and elastic modulus. Generally, a more significant amount of the α phase in the Ti-15Nb alloy increased the elastic modulus value but decreased the microhardness value. After the RC treatment, the results demonstrated that the Ti-15Nb alloy did not present cytotoxic effects on the osteogenic cells. In addition, we did not find variations in the cell quantity in the microscopy results that could suggest cell adhesion or proliferation modification

Influence of Heat Treatment and Oxygen Doping on the Mechanical Properties and Biocompatibility of Titanium-Niobium Binary Alloys

The most commonly used titanium (Ti)-based alloy for biological applications is Ti-6Al-4V, but some studies associate the vanadium (V) with the cytotoxic effects and adverse reactions in tissues, while aluminum (Al) has been associated with neurological disorders. Ti-Nb alloys belong to a new class of Ti-based alloys with no presence of Al and V and with elasticity modulus values that are very attractive for use as a biomaterial. It is well known that the presence of interstitial elements (such as oxygen, for example) changes the mechanical properties of alloys significantly, particularly the elastic properties, the same way that heat treatments can change the microstructure of these alloys. This article presents the effect of heat treatment and oxygen doping in some mechanical properties and the biocompatibility of three alloys of the Ti-Nb system, characterized by density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, in vitro cytotoxicity, and mechanical spectroscopy.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Preparation and characterization of Ti-15Mo alloy used as biomaterial

With the increase in life expectancy, biomaterials have become an increasingly important focus of research because they are used to replace parts and functions of the human body, thus contributing to improved quality of life. In the development of new biomaterials, the Ti-15Mo alloy is particularly significant. In this study, the Ti-15Mo alloy was produced using an arc-melting furnace and then characterized by density, X-ray diffraction, optical microscopy, hardness and dynamic elasticity modulus measurements, and cytotoxicity tests. The microstructure was obtained with β predominance. Microhardness, elasticity modulus, and cytotoxicity testing results showed that this material has great potential for use as biomaterial, mainly in orthopedic applications