Effects of TGF-ß1 on mineralization mediated by rat calvaria-derived osteogenic cells.

In this study, we have analyzed the viability and cell growth, as well as, the mineralization of extracellular matrix (ECM) by alizarin red and von Kossa staining of calvaria-derived osteogenic cultures, treated with TGF-ß1 alone or associated with Dex comparing with acid ascorbic (AA) + ß-glicerophosphate (ßGP) (positive mineralization control). The expression of the noncollagenous proteins bone sialoprotein (BSP), osteopontin (OPN) and fibronectin (FN) were evaluated by indirect immunofluorescence. In addition, the main ultrastructural morphological findings were assessed by transmission electron microscopy. Osteogenic cells were isolated of calvaria bone from newborn (2-day-old) Wistar rats were treated with TGF-ß1 alone or with dexamethasone for 7, 10, and 14 days. As positive mineralization control, the cells were supplemented only with AA+ ßGP. As negative control, the cells were cultured with basal medium (α-MEM + 10%FBS + 1%gentamicin). The treatment with TGF-ß1, even when combined with Dex, decreased the viability and cell growth when compared with the positive control. Osteoblastic cell cultures were positive to alizarin red and von Kossa stainings after AA + ßGP and Dex alone treatments. Positive immunoreaction was found for BSP, OPN and FN in all studied treatments. Otherwise, when the cell cultures were supplemented with TGF-ß1 and TGF-ß1 + Dex, no mineralization was observed in any of the studied periods. These present findings suggest that TGF-ß1, in the studied in vitro doses, inhibits the proliferation and differentiation of osteoblastic cells by impairment of nodule formation.

Influence of Oxygen Content and Microstructure on the Mechanical Properties and Biocompatibility of Ti-15 wt%Mo Alloy Used for Biomedical Applications.

The Ti-15Mo alloy has its mechanical properties strongly altered by heat treatments and by addition of interstitial elements, such as, oxygen, for example. In this sense, the objective of this paper is to analyze the effect of the introduction of oxygen in selected mechanical properties and the biocompatibility of Ti-15Mo alloy. The samples used in this study were prepared by arc-melting and characterized by density measurements, X-ray diffraction, scanning electron microscopy, microhardness, modulus of elasticity, and biocompatibility tests. Hardness measurements were shown to be sensitive to concentration of oxygen. The modulus results showed interstitial influence in value; this was verified under several conditions to which the samples were exposed. Cytotoxicity tests conducted in vitro showed that the various processing conditions did not alter the biocompatibility of the material.

The Influence of Small Quantities of Oxygen in the Structure, Microstructure, Hardness, Elasticity Modulus and Cytocompatibility of Ti-Zr Alloys for Dental Applications.

The mechanical properties of Ti alloys are changed significantly with the addition of interstitial elements, such as oxygen. Because oxygen is a strong stabilizer of the α phase and has an effect on hardening in a solid solution, it has aroused great interest in the biomedical area. In this paper, Ti-Zr alloys were subjected to a doping process with small amounts of oxygen. The influence of interstitial oxygen in the structure, microstructure and some selected mechanical properties of interest for use as biomaterial and biocompatibility of the alloys were analyzed. The results showed that in the range of 0.02 wt% to 0.04 wt%, oxygen has no influence on the structure, microstructure or biocompatibility of the studied alloys, but causes hardening of the alloys, increasing the values of the microhardness and causing variation in the elasticity modulus values.

In vitro effects of ascorbic acid and ß-glycerophosphate on human gingival fibroblast cells.

Ascorbic acid (AA) and ß-glycerophosphate (ßG) are considered in vitro osteogenic factors important to the differentiation of osteoblastic progenitor and dental pulp cells into mineralized tissue-forming cells. So, the present study investigated in vitro if these mineralizing inducible factors (AA and ßG) could influence differentiation of human gingival fibroblasts when compared with human pulp cells and osteogenic cells derived from rat calvaria cultured. The expression of osteopontin (OPN) and osteoadherin (OSAD) was analyzed by indirect immunofluorescence, immunocytochemistry as well as Western-blotting. In addition, the main ultrastructural aspects were also investigated. No mineralized matrix formation occurred on gingival fibroblasts induced with AA+ßG. On these cells, no expression of OPN and OSAD was observed when compared with pulp cells, pulp cells induced with AA+ßG as well as osteogenic cells. Ultrastructure analysis additionally showed that gingival fibroblasts exhibited typical fibroblast morphology with no nodule formation. The present findings showed that AA and ßG could not promote a mineralized cell differentiation of human gingival fibroblasts and confirm that human dental pulp cells, as the osteogenic cells, are capable to form a mineralized extracellular.