Efectos osteogénicos de la PTHrP (107-111) cargada en biocerámicas en un modelo de regeneración ósea tras un defecto cavitario en el fémur de conejo

Introducción: La proteína relacionada con la parthormona (PTHrP), un factor abundante en el tejido óseo, es un importante modulador de la formación ósea. Se ha demostrado que la PTHrP (107-111), conocida como osteostatina, cargada en el material cerámico mesoporoso SBA-15, ejerce acciones osteogénicas in vitro. Objetivo: Comprobar si dicho material y una versión funcionalizada del mismo (C8-SBA-15) promueven la reparación ósea en un modelo de defecto cavitario en el fémur del conejo. Material y métodos: Para ello se han llevado a cabo estudios histológicos e inmunohistoquímicos y de microtomografía computerizada (µCT). Resultados: Tras la implantación de los biomateriales no se observaron niveles significativos de inflamación ni resorción ósea (4 y 8 semanas). A las 8 semanas las biocerámicas no cargadas con la osteostatina se encontraban separadas de la médula ósea por una cápsula fibrosa, que disminuía de forma significativa en presencia del péptido. Se observó (por µCT) un aumento de la neo-formación ósea a diferentes distancias de los biomateriales, principalmente en los cargados con la osteostatina. Además, estos resultados fueron confirmados por inmunohistoquímica de marcadores osteoblásticos. Conclusión: Nuestros hallazgos sugieren que estas biocerámicas cargadas con la osteostatina son una buena estrategia para acelerar la regeneración ósea

Identifying priority sites for the conservation of freshwater fish biodiversity in a Mediterranean basin with a high degree of threatened endemics

The Guadiana River basin’s freshwater fish species richness, endemicity and threatened status (92% of native species are threatened) highlight the need for a large-scale study to identify priority areas for their conservation. One of the most common problems in conservation planning is the assessment of a site’s relative value for the conservation of regional biodiversity. Here we used a two-tiered approach, which integrates an assessment of biodiversity loss and the evaluation of conservation value through site-specific measures. These measures based on the reference condition approach introduce the ability to make objective comparisons throughout the Guadiana River basin, thus avoiding a priori target areas. We identified a set of biodiversity priority areas of special conservation significance—which contain rare taxa as well as intact fish communities—because of their outstanding contribution to the basin’s biodiversity. The inclusion of complete sub-basins in these priority areas might guarantee an optimal solution in terms of spatial aggregation and connectivity. However, the high spatial fragmentation to which the Guadiana River basin is submitted due to river regulation highlights the necessity of a systematic approach to evaluate the capability of the identified priority areas to maintain the Guadiana’s freshwater fish biodiversity

In vitro bioactivity, cytocompatibility, and antibiotic release profile of gentamicin sulfate-loaded borate bioactive glass/chitosan composites

Borate bioactive glass-based composites have been attracting interest recently as an osteoconductive carrier material for local antibiotic delivery. In the present study, composites composed of borate bioactive glass particles bonded with a chitosan matrix were prepared and evaluated in vitro as a carrier for gentamicin sulfate. The bioactivity, degradation, drug release profile, and compressive strength of the composite carrier system were studied as a function of immersion time in phosphate-buffered saline at 37 °C. The cytocompatibility of the gentamicin sulfate-loaded composite carrier was evaluated using assays of cell proliferation and alkaline phosphatase activity of osteogenic MC3T3-E1 cells. Sustained release of gentamicin sulfate occurred over ~28 days in PBS, while the bioactive glass converted continuously to hydroxyapatite. The compressive strength of the composite loaded with gentamicin sulfate decreased from the as-fabricated value of 24 ± 3 MPa to ~8 MPa after immersion for 14 days in PBS. Extracts of the soluble ionic products of the borate glass/chitosan composites enhanced the proliferation and alkaline phosphatase activity of MC3T3-E1 cells. These results indicate that the gentamicin sulfate-loaded composite composed of chitosan-bonded borate bioactive glass particles could be useful clinically as an osteoconductive carrier material for treating bone infection