Suchergebnisse

A wide variety of biomaterials and bioactive molecules have been applied as scaffolds in neuronal tissue engineering. However, creating devices that enhance the regeneration of nervous system injuries is still a challenge, due the difficulty in providing an appropriate environment for cell growth and differentiation and active stimulation of nerve regeneration. In recent years, bacterial cellulose (BC) has emerged as a promising biomaterial for biomedical applications due its properties, such as high crystallinity, an ultrafine fiber network, high tensile strength and biocompatibility. The small signaling peptides found in the proteins of extracellular matrix are described in the literature as promoters of adhesion and proliferation for several cell lineages on different surfaces. In this work, the peptide IKVAV was fused to a carbohydrate-binding module (CBM3) and used to modify BC surfaces, with the goal of promoting neuronal and mesenchymal stem cell (MSC) adhesion. The recombinant proteins IKVAV-CBM3 and (19)IKVAV-CBM3 were successfully expressed in E. coli, purified through affinity chromatography and stably adsorbed to the BC membranes. The effect of these recombinant proteins, as well as RGD-CBM3, on cell adhesion was evaluated by MTS colorimetric assay. The results showed that the (19)IKVAV-CBM3 was able to significantly improve the adhesion of both neuronal and mesenchymal cells and had no effect on the other cell lineages tested. The MSC neurotrophin expression in cells grown on BC membranes modified with the recombinant proteins was also analyzed. ; Renata A. N. Pertile gratefully acknowledges support by the Programme Al beta an, the European Union Programme of High Level Scholarships for Latin America (Scholarship No. E07D401931BR). The author Susana Moreira is recipient of a SFRH/BPD/64726/2009 fellowship from Fundacao para a Ciencia e a Tecnologia (FCT, Portugal). Fabia K. Andrade is the recipient of a fellowship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, ...

The bacterial cellulose (BC) secreted by G. xylinus is a network of pure cellulose nanofibers, which has high crystallinity, wettability and mechanical strength. These characteristics make BC an excellent material for tissue engineering constructs, noteworthy for artificial vascular grafts. In this work, the in vivo biocompatibility of BC membranes produced by two G. xylinus strains was analyzed through histological analysis of long-term subcutaneous implants in the mice. The BC implants caused a mild and benign inflammatory reaction that decreased along time and did not elicit a foreign body reaction. A tendency to calcify over time, which may be related to the porosity of the BC implants, was observed, especially amo the less poro s BC-1 implants. In addition, the potential toxicity of BC nanofibers - obtained by chemical-mechanical treatment of BC membranes - subcutaneously implanted in mice was analysed through bone marrow flow cytometry, blood and histological analyses. After 2 and 4 months post implantation, the nanofibers implants were found to accumulate cytoplasmically, in subcutaneous foamy macrophages aggregates. Moreover, no differences were observed between the controls and implanted animals in thymocyte populations and in B lymphocyte precursors and myeloid cells in the bone marrow. ; R. A. N. P. gratefully acknowledges support by the Programme Alssan, the European Union Programme of High Level Scholarships for Latin America (Scholarship No. E07D401931BR). S. M. is recipient of a SFRH/BPD/64726/2009 fellowship from Fundacao para a Ciencia e a Tecnologia (FCT, Portugal). R. M. G. da C. (SFRH/BD/37565/2007) and A. C. (SFRH/BD/31354/2006) are recipients of a PhD fellowship from Fundacao para a Ciencia e a Tecnologia (FCT, Portugal). Funding by FCT and the program COMPETE of the project PTDC/EBB-EBI/112170/2009 is ...