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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.

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.

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.

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.

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.

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