In vitro and in vivo osteogenic potential of niobium-doped 45S5 bioactive glass:A comparative study

In vitro and in vivo experiments were undertaken to evaluate the solubility, apatite-forming ability, cytocompatibility, osteostimulation, and osteoinduction for a series of Nb-containing bioactive glass (BGNb) derived from composition of 45S5 Bioglass. Inductively coupled plasma optical emission spectrometry (ICP-OES) revealed that the rate at which Na, Ca, Si, P, and Nb species are leached from the glass decrease with the increasing concentration of the niobium oxide. The formation of apatite as a function of time in simulated body fluid was monitored by 31P Magic Angle Spinning (MAS) Nuclear magnetic resonance spectroscopy. Results showed that the bioactive glasses: Bioglass 45S5 (BG45S5) and 1 mol%-Nb-containing-bioactive glass (BGSN1) were able to grow apatite layer on their surfaces within 3 h, while glasses with higher concentrations of Nb2O5 (2.5 and 5 mol%) took at least 12 h. Nb-substituted glasses were shown to be compatible with bone marrow-derived mesenchymal stem cells (BMMSCs). Moreover, the bioactive glass with 1 mol% Nb2O5 significantly enhanced cell proliferation after 4 days of treatment. Concentrations of 1 and 2.5 mol% Nb2O5 stimulated osteogenic differentiation of BMMSCs after 21 days of treatment. For the in vivo experiments, trial glass rods were implanted into circular defects in rat tibia in order to evaluate their osteoconductivity and osteostimulation. Two morphometric parameters were analyzed: (a) thickness of new-formed bone layer and (b) area of new-formed subperiostal bone. Results showed that BGNb bioactive glass is osteoconductive and osteostimulative. Therefore, these results indicate that Nb-substituted glass is suitable for biomedical applications

Microvascular reactivity in type 1 diabetics Reatividade microvascular em diabéticos tipo 1 Microvascular reactivity in DM1

ABSTRACT Objective: To evaluate whether differences are present in microvascular response to the schemia induced by dynamic videocapillaroscopy (VCD), through analysis of the measured capillar transverse segment area (CTSA) in patients with type 1 diabetes mellitus (T1DM). Methods: The vascular reactivity of the CTSA was studied by VCD, using a reactive hyperemia test in 61 volunteers, being 31 healthy controls without diabetes family history (Group 1) and 30 patients with T1DM without complications (Group 2). The images were captured every two seconds, during reperfusion after one minute induced ischaemia, and they were analyzed by the program Studio Version 8 and Motic Image Plus. The pre-ischemia capillary transverse segment (basal area, BA), the maximum strain post-ischemia (maximum area, MA), and time to achieve it (MAt) were measured during reperfusion, and the increased area percentage (Ap) was estimated. Results: The mean differences between groups were evaluated by the t-test. The median comparisons between the groups were studied by the Mann-Whitney test. There was no difference in BA between the groups. The Ap was significantly lower among the diabetic patients, and there was a significant increase in the Mat among the patients of Group 2 when compared to Group 1. Conclusions: These data suggest that type 1 diabetes provokes earlier endothelial dysfunction, before the onset of clinically detectable degenerative complications. The outcomes from these alterations need further studies. Arq Bras Endocrinol Metab. 2009;53(6):741-6 Keywords Diabetes mellitus; microcirculation; angioscopy microscopy; endothelium-abnormalities RESUMO Objetivo: Avaliar se há diferença de resposta microcirculatória à isquemia induzida pela videocapilaroscopia dinâmica (VCD), por meio da análise de medida da área do segmento transverso capilar (ASTC) em pacientes com diabetes melito tipo 1 (DMT1). Métodos: A reatividade vascular do ASTC foi estudada pela VCD usando o teste de hiperemia reativa em 61 voluntários, sendo 31 controles sadios sem história familiar de diabetes (Grupo 1) e 30 pacientes com DMT1, sem complicações (Grupo 2). As imagens foram capturadas a cada dois segundos, durante a reperfusão após um minuto de isquemia induzida, e analisadas pelo programa Studio Version 8 e Motic Image Plus. O segmento transverso pré-isquemia (área basal, AB), a área máxima pós-isquemia (área máxima, AM) e o tempo para alcançá-la foram medidos durante a reperfusão, e o percentual de incremento foi estimado. Resultados: As principais diferenças entre os grupos foram avaliadas pelo teste t. As médias comparativas entre os grupos foram avaliadas pelo teste Mann-Whitney. Não houve diferença na área basal entre os dois grupos. O percentual de incremento foi significativamente menor entre os pacientes diabéticos e houve um aumento significativo no ASTC entre os pacientes do Grupo 2 quando comparados com o Grupo 1. Conclusões: Os dados sugerem que o diabetes tipo 1 provoca disfunção endotelial precoce, antes mesmo de complicações degenerativas serem detectadas clinicamente. Os fatores que levam a essas alterações necessitam de estudos adicionais. Arq Bras Endocrinol Metab. 2009;53(6):741-6 Descritores Diabetes melito; microcirculação; angioscopia microscópica; endotélio-anormalidade

Methodological implications on quantitative studies of cytocompatibility in direct contact with bioceramic surfaces

6 p. : il., tabCell adhesion, proliferation and differentiation are important specific parameters to be evaluated on biocompatibility studies of candidate biomaterials for clinical applications. Several different methodologies have been employed to study, both qualitative and quantitatively, the direct interactions of ceramic materials with cultured mammal and human cells. However, while quantitatively evaluating cell density, viability and metabolic responses to test materials, several methodological challenges may arise, either by impairing the use of some widely applied techniques, or by generating false or conflicting results. In this work, we tested the inherent interference of different representative calcium phosphate ceramic surfaces (stoichiometric dense and porous hydroxyapatite (HA) and cation-substituted apatite tablets) on different tests for quantitative evaluation of osteoblast adhesion and metabolism, either based on direct cell counting after trypsinization, colorimetric assays (XTT, Neutral Red and Crystal Violet) and fluorescence microscopy. Cell adhesion estimation after trypsinization was highly dependent on the time of treatment, and the group with the highest level of estimated adhesion was inverted from 5 to 20 minutes of exposition to trypsin. Both dense and porous HA samples presented high levels of background adsorption of the Crystal Violet dye, impairing cell detection. HA surfaces also were able to adsorb high levels of fluorescent dyes (DAPI and phalloidin-TRITC), generating backgrounds which, in the case of porous HA, impaired cell detection and counting by image processing software (Image Pro Plus 6.0). We conclude that the choice for the most suitable method for cell detection and estimation is highly dependent on very specific characteristics of the studied material, and methodological adaptations on well established protocols must always be carefully taken on consideration

Biocompatibility of carbonated hydroxyapatite nanoparticles with different crystallinities

6 p. : il., tab.Carbonated apatite (CHA) is commonly considered a promising synthetic material for biomedical applications in orthopedic and dental surgery due to its biocompatibility, bioresorption and bioactivity. CHA5, CHA37 and CHA90 powders were synthesized from wet method and the DRX patterns showed that the crystallinity and particle size of CHA samples increased proportionally with the synthesis temperature. Powder extracts medium were obtained from each sample to interact with MC3T3-E1 osteoblastics cells. It was evaluated morphology, citotoxicity, pH and Ca2+ concentration. Citotoxicity assays showed high metabolic activity on all samples when compared to control. The polygonal shaped and the confluent monolayer observed in control cells progressively changed according to the crystallinity increase of samples. Cells under mitosis and spindle-like shaped where the main alterations observed. In addition the cell viability could be sensitive to the acid reactivity and crystallinity of carbonated apatite samples