Icvs 3Bs Pt Government Associ Laboratory

Braga, Portugal

Icvs 3Bs Pt Government Associ Laboratory

Braga, Portugal
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Silva S.S.,University of Minho | Silva S.S.,Icvs 3Bs Pt Government Associ Laboratory | Caridade S.G.,University of Minho | Caridade S.G.,Icvs 3Bs Pt Government Associ Laboratory | And 4 more authors.
Carbohydrate Polymers | Year: 2013

The positive interaction between polysaccharides with active phytochemicals found in medicinal plants may represent a strategy to create active wound dressing materials useful for skin repair. In the present work, blended membranes composed of chitosan (Cht) and aloe vera gel were prepared through the solvent casting, and were crosslinked with genipin to improve their properties. Topography, swelling, wettability, mechanical properties and in vitro cellular response of the membranes were investigated. With the incorporation of aloe vera gel into chitosan solution, the developed chitosan/aloe-based membranes displayed increased roughness and wettability; while the genipin crosslinking promoted the formation of stiffer membranes in comparison to those of the non-modified membranes. Moreover, in vitro cell culture studies evidenced that the L929 cells have high cell viability, confirmed by MTS test and calcein-AM staining. The findings suggested that both blend compositions and crosslinking affected the physico-chemical properties and cellular behavior of the developed membranes. © 2013 Elsevier Ltd. All rights reserved.

Soto A.M.,Tampere University of Technology | Soto A.M.,BioMediTech Institute of Biosciences and Medical Technology | Koivisto J.T.,BioMediTech Institute of Biosciences and Medical Technology | Koivisto J.T.,Tampere University of Technology | And 15 more authors.
Langmuir | Year: 2016

The microstructure and permeability are crucial factors for the development of hydrogels for tissue engineering, since they influence cell nutrition, penetration, and proliferation. The currently available imaging methods able to characterize hydrogels have many limitations. They often require sample drying and other destructive processing, which can change hydrogel structure, or they have limited imaging penetration depth. In this work, we show for the first time an alternative nondestructive method, based on optical projection tomography (OPT) imaging, to characterize hydrated hydrogels without the need of sample processing. As proof of concept, we used gellan gum (GG) hydrogels obtained by several cross-linking methods. Transmission mode OPT was used to analyze image microtextures, and emission mode OPT to study mass transport. Differences in hydrogel structure related to different types of cross-linking and between modified and native GG were found through the acquired Haralicks image texture features followed by multiple discriminant analysis (MDA). In mass transport studies, the mobility of FITC-dextran (MW 20, 150, 2000 kDa) was analyzed through the macroscopic hydrogel. The FITC-dextran velocities were found to be inversely proportional to the size of the dextran as expected. Furthermore, the threshold size in which the transport is affected by the hydrogel mesh was found to be 150 kDa (Stokes radii between 69 and 95 Å). On the other hand, the mass transport study allowed us to define an index of homogeneity to assess the cross-linking distribution, structure inside the hydrogel, and repeatability of hydrogel production. As a conclusion, we showed that the set of OPT imaging based material characterization methods presented here are useful for screening many characteristics of hydrogel compositions in relatively short time in an inexpensive manner, providing tools for improving the process of designing hydrogels for tissue engineering and drugs/cells delivery applications. © 2016 American Chemical Society.

Yan L.-P.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Yan L.-P.,Icvs 3Bs Pt Government Associ Laboratory | Salgado A.J.,Icvs 3Bs Pt Government Associ Laboratory | Salgado A.J.,University of Minho | And 7 more authors.
Journal of Bioactive and Compatible Polymers | Year: 2013

Macro/microporous silk/nano-sized calcium phosphate scaffolds (SC16) with bioactive and superior physicochemical properties are currently being developed. In this study, we evaluated the new bone formation ability in rat femur of the SC16 scaffolds in vivo, using silk fibroin scaffolds (S16) as control. The CaP distribution profile in the scaffolds was characterized by micro-computed tomography and the CaP phase was found to be distributed homogeneously in the SC16 scaffolds. Mineralization was only observed in SC16 scaffolds, and both scaffolds gradually degraded with time. By staining the explants, new bone growth was observed directly on the SC16 surface and with higher density than that observed on the S16 scaffolds. These results demonstrated that the SC16 hybrid scaffolds are osteoconductive and can be good candidates for bone tissue engineering as they promote superior de novo bone formation. © The Author(s) 2013.

Rolanda C.,Hospital Braga | Rolanda C.,University of Minho | Rolanda C.,Icvs 3Bs Pt Government Associ Laboratory | Caetano A.C.,Hospital Braga | And 4 more authors.
Best Practice and Research: Clinical Gastroenterology | Year: 2013

Endoscopy adverse events (AEs), or complications, are a rising concern on the quality of endoscopic care, given the technical advances and the crescent complexity of therapeutic procedures, over the entire gastrointestinal and bilio-pancreatic tract. In a small percentage, not established, there can be real emergency conditions, as perforation, severe bleeding, embolization or infection. Distinct variables interfere in its occurrence, although, the awareness of the operator for their potential, early recognition, and local organized facilities for immediate handling, makes all the difference in the subsequent outcome. This review outlines general AEs' frequencies, important predisposing factors and putative prophylactic measures for specific procedures (from conventional endoscopy to endoscopic cholangio-pancreatography and ultrasonography), with comprehensive approaches to the management of emergent bleeding and perforation. © 2013 Elsevier Ltd. All rights reserved.

Carvalho P.P.,Louisiana State University | Carvalho P.P.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Carvalho P.P.,Icvs 3Bs Pt Government Associ Laboratory | Leonor I.B.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | And 10 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2014

The repair of large bony defects remains challenging in the clinical setting. Human adipose-derived stromal/stem cells (hASCs) have been reported to differentiate along different cell lineages, including the osteogenic. The objective of the present study was to assess the bone regeneration potential of undifferentiated hASCs loaded in starch-polycaprolactone (SPCL) scaffolds, in a critical-sized nude mice calvarial defect. Human ASCs were isolated from lipoaspirate of five female donors, cryopreserved, and pooled together. Critical-sized (4 mm) calvarial defects were created in the parietal bone of adult male nude mice. Defects were either left empty, treated with an SPCL scaffold alone, or SPCL scaffold with human ASCs. Histological analysis and Micro-CT imaging of the retrieved implants were performed. Improved new bone deposition and osseointegration was observed in SPCL loaded with hASC engrafted calvarial defects as compared to control groups that showed little healing. Nondifferentiated human ASCs enhance ossification of nonhealing nude mice calvarial defects, and wet-spun SPCL confirmed its suitability for bone tissue engineering. This study supports the potential translation for ASC use in the treatment of human skeletal defects. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3102-3111, 2014. © 2013 Wiley Periodicals, Inc.

Mihaila S.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Mihaila S.M.,Icvs 3Bs Pt Government Associ Laboratory | Popa E.G.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Popa E.G.,Icvs 3Bs Pt Government Associ Laboratory | And 6 more authors.
Biomacromolecules | Year: 2014

Recent achievements in the area of tissue engineering (TE) have enabled the development of three-dimensional (3D) cell-laden hydrogels as in vitro platforms that closely mimic the 3D scenario found in native tissues. These platforms are extensively used to evaluate cellular behavior, cell-cell interactions, and tissue-like formation in highly defined settings. In this study, we propose a scalable and flexible 3D system based on microsized hydrogel fibers that might be used as building blocks for the establishment of 3D hydrogel constructs for vascularized bone TE applications. For this purpose, chitosan (CHT) coatedκ-carrageenan (κ-CA) microfibers were developed using a two-step procedure involving ionotropic gelation (for the fiber formation) ofκ-CA and its polyelectrolyte complexation with CHT (for the enhancement of fiber stability). The performance of the obtained fibers was assessed regarding their swelling and stability profiles, as well as their ability to carry and, subsequently, promote the outward release of microvascular-like endothelial cells (ECs), without compromising their viability and phenotype. Finally, the possibility of assembling and integrating these cell-laden fibers within a 3D hydrogel matrix containing osteoblast-like cells was evaluated. Overall, the obtained results demonstrate the suitability of the microsizedκ-CA fibers to carry and deliver phenotypically apt microvascular-like ECs. Furthermore, it is shown that it is possible to assemble these cell-laden microsized fibers into 3D heterotypic hydrogels constructs. This in vitro 3D platform provides a versatile approach to investigate the interactions between multiple cell types in controlled settings, which may open up novel 3D in vitro culture techniques to better mimic the complexity of tissues. © 2014 American Chemical Society.

Bacelar A.H.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Bacelar A.H.,Icvs 3Bs Pt Government Associ Laboratory | Silva-Correia J.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Silva-Correia J.,Icvs 3Bs Pt Government Associ Laboratory | And 4 more authors.
Journal of Materials Chemistry B | Year: 2016

Gellan gum, a microbial exopolysaccharide fermentation product of Pseudomonas elodea, is a natural biomaterial that has shown promise for tissue engineering and regenerative medicine applications. Although this exopolysaccharide possesses many advantages, such as interesting physicochemical properties and non-cytotoxicity, the mechanical properties and processability of gellan gum are not totally satisfactory in different tissue engineering contexts, i.e. gellan gum hydrogels are mechanically weak and the high gelling temperature is also unfavourable. An additional critical limitation is the lack of specific attachment sites for anchorage-dependent cells. However, the multiple hydroxyl groups and the free carboxyl per repeating unit of gellan gum can be used for chemical modification and functionalization in order to optimize its physicochemical and biological properties. A number of physical modification approaches have also been employed. This review outlines the recent progress in gellan gum hydrogels and their derivatives, and identifies the new challenges in tissue engineering, provided by blending and/or chemical modification. © 2016 The Royal Society of Chemistry.

Oliveira S.M.,3Bs Research Group Biomaterials | Oliveira S.M.,Icvs 3Bs Pt Government Associ Laboratory | Silva T.H.,3Bs Research Group Biomaterials | Silva T.H.,Icvs 3Bs Pt Government Associ Laboratory | And 4 more authors.
Journal of Materials Chemistry B | Year: 2013

The understanding of both cell-extracellular matrix (ECM) and cell-material interactions is crucial for the success of implantable biomaterials including tissue engineering devices. ECM is rich in sulfated and aminated glycosaminoglycans and proteoglycans. The development of synthetic models containing those chemical groups is thus of major interest. Thin coatings of polysaccharides with controlled sulfur and nitrogen contents were developed by layer-by-layer assembly. In particular, the multilayers were prepared by assembling chitosan with κ-, ι- and λ-carrageenan (increasing sulfur content). The nanostructured multilayers were characterized by quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), scanning electron microscopy (SEM), water contact angle, X-ray photoelectron spectroscopy (XPS) and used as models to study the effect of the sulfate groups over the behavior of osteoblast-like cells. The biomimetic coatings increased the alkaline phosphatase (ALP) activity and proliferation compared with unmodified polycaprolactone surfaces. Biomineralization increase with the presence of the coatings is significantly higher on ι-carrageenan coatings, suggesting that the sulfate groups may interact positively with molecules involved in the osteoblastic activity as it occurs in the natural ECM. The developed nanocoatings can constitute an interesting model to understand the biological influence of the sulfate and amine groups existing on the surface of biomaterials. This journal is © The Royal Society of Chemistry 2013.

Yang Y.,Martin Luther University of Halle Wittenberg | Kowitsch A.,Martin Luther University of Halle Wittenberg | Ma N.,Martin Luther University of Halle Wittenberg | Mader K.,Martin Luther University of Halle Wittenberg | And 5 more authors.
Journal of Bioactive and Compatible Polymers | Year: 2016

Glycosaminoglycans are able to bind many growth factors and adhesive proteins, which affect cell activities such as adhesion, migration, growth and differentiation. Chondroitin sulphate, hyaluronan, sulphated hyaluronan and heparin were oxidised here (aldehyde glycosaminoglycans) to generate aldehydes on vicinal hydroxyl groups of the uronic monomers of glycosaminoglycans for subsequent direct covalent binding to amino-terminated model substrata. The properties of modified surfaces were monitored by water contact angle, zeta potential, ellipsometry measurements and atomic force microscopy showing successful immobilisation of aldehyde glycosaminoglycans. Wetting properties and zeta potentials were related to sulphate content of aldehyde glycosaminoglycans with aldehyde heparin as most wettable and negative surface and aldehyde hyaluronan as the least. The thickness of surface layers measured by ellipsometry indicated a predominant side-on immobilisation of all aldehyde glycosaminoglycans. Atomic force microscopy studies showed that immobilisation of aldehyde hyaluronan lead to a rather smooth surface coating while immobilisation of sulphated aldehyde glycosaminoglycans was characterised by a globular appearance of surfaces with higher roughness. The experiments with human fibroblast studying adhesion under serum-free conditions were carried out to learn about bioactivity of aldehyde glycosaminoglycans. It was observed that the increase in sulphation degree of aldehyde glycosaminoglycans was accompanied by increased adhesion and spreading of cells with stronger expression of focal adhesions and cytoskeletal structures. By contrast, cell adhesion and spreading were lower on aldehyde hyaluronan. Immunofluorescence staining of cells in contact with aldehyde hyaluronan revealed a stronger expression of CD44, which can represent an alternative route of cell adhesion. The results show that oxidised glycosaminoglycans can be successfully applied for the development of bioactive surface coatings. The created biomimetic microenvironment may be useful to engineer surfaces of implants and scaffolds for tissue regeneration. © SAGE Publications.

Silva S.S.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Silva S.S.,Icvs 3Bs Pt Government Associ Laboratory | Duarte A.R.C.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Duarte A.R.C.,Icvs 3Bs Pt Government Associ Laboratory | And 6 more authors.
Journal of Bioactive and Compatible Polymers | Year: 2013

An alternative, green method was used to develop chitin-based biocomposite (ChHA) materials by an integrated strategy using ionic liquids, supercritical fluid drying, and salt leaching. ChHA matrices were produced by dissolving chitin in 1-butyl-methylimidazolium acetate along with salt and/or hydroxyapatite particles and then subsequent drying. The ChHA composite formed had a heterogeneous porous microstructure with 65%-85% porosity and pore sizes in the range of 100-300 μm. The hydroxyapatite was found to be well distributed within the composite structures and had a positive effect in the viability and proliferation of osteoblast-like cells, in vitro. Our findings indicate that these ChHA matrices have potential applications in bone tissue engineering. © The Author(s) 2013.

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