Browsing by Author "Coutinho, Paula Isabel Teixeira Gonçalves"
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- Dextran-based hydrogel containing chitosan microparticles loaded with growth factors to be used in wound healingPublication . Ribeiro, MP.; Morgado, Patrícia I.; Miguel, Sónia P.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraSkin injuries are traumatic events, which are seldom accompanied by complete structural and functional restoration of the original tissue. Different strategies have been developed in order to make the wound healing process faster and less painful. In the present study in vitro and in vivo assays were carried out to evaluate the applicability of a dextran hydrogel loaded with chitosan microparticles containing epidermal and vascular endothelial growth factors, for the improvement of the wound healing process. The carriers' morphology was characterized by scanning electron microscopy. Their cytotoxicity profile and degradation by-products were evaluated through in vitro assays. In vivo experiments were also performed to evaluate their applicability for the treatment of skin burns. The wound healing process was monitored through macroscopic and histological analysis. The macroscopic analysis showed that the period for wound healing occurs in animals treated with microparticle loaded hydrogels containing growth factors that were considerably smaller than that of control groups. Moreover, the histological analysis revealed the absence of reactive or granulomatous inflammatory reaction in skin lesions. The results obtained both in vitro and in vivo disclosed that these systems and its degradation by-products are biocompatible, contributed to the re-establishment of skin architecture and can be used in a near future for the controlled delivery of other bioactive agents used in regenerative medicine.
- Electrospun Polycaprolactone/Aloe Vera_Chitosan Nanofibrous Asymmetric Membranes Aimed for Wound Healing ApplicationsPublication . Miguel, Sónia; Ribeiro, MP.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraToday, none of the wound dressings available on the market is fully capable of reproducing all the features of native skin. Herein, an asymmetric electrospun membrane was produced to mimic both layers of skin. It comprises a top dense layer (manufactured with polycaprolactone) that was designed to provide mechanical support to the wound and a bottom porous layer (composed of chitosan and Aloe Vera) aimed to improve the bactericidal activity of the membrane and ultimately the healing process. The results obtained revealed that the produced asymmetric membranes displayed a porosity, wettability, as well as mechanical properties similar to those presented by the native skin. Fibroblast cells were able to adhere, spread, and proliferate on the surface of the membranes and the intrinsic structure of the two layers of the membrane is capable of avoiding the invasion of microorganisms while conferring bioactive properties. Such data reveals the potential of these asymmetric membranes, in the near future, to be applied as wound dressings.
- In Vivo High-Content Evaluation of Three-Dimensional Scaffolds BiocompatibilityPublication . Oliveira, Mariana; Ribeiro, MP.; Miguel, Sónia; Neto, Ana; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim Sobreira; Mano, João F.While developing tissue engineering strategies, inflammatory response caused by biomaterials is an unavoidable aspect to be taken into consideration, as it may be an early limiting step of tissue regeneration approaches. We demonstrate the application of flat and flexible films exhibiting patterned high-contrast wettability regions as implantable platforms for the high-content in vivo study of inflammatory response caused by biomaterials. Screening biomaterials by using high-throughput platforms is a powerful method to detect hit spots with promising properties and to exclude uninteresting conditions for targeted applications. High-content analysis of biomaterials has been mostly restricted to in vitro tests where crucial information is lost, as in vivo environment is highly complex. Conventional biomaterials implantation requires the use of high numbers of animals, leading to ethical questions and costly experimentation. Inflammatory response of biomaterials has also been highly neglected in high-throughput studies. We designed an array of 36 combinations of biomaterials based on an initial library of four polysaccharides. Biomaterials were dispensed onto biomimetic superhydrophobic platforms with wettable regions and processed as freeze-dried three-dimensional scaffolds with a high control of the array configuration. These chips were afterward implanted subcutaneously in Wistar rats. Lymphocyte recruitment and activated macrophages were studied on-chip, by performing immunocytochemistry in the miniaturized biomaterials after 24 h and 7 days of implantation. Histological cuts of the surrounding tissue of the implants were also analyzed. Localized and independent inflammatory responses were detected. The integration of these data with control data proved that these chips are robust platforms for the rapid screening of early-stage in vivo biomaterials' response.
- Microencapsulated chitosan–dextran sulfate nanoparticles for controled delivery of bioactive molecules and cells in bone regenerationPublication . Valente, Joana; Gaspar, Vítor Manuel Abreu; Antunes, Bernardo Paiva; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraThis research work aimed to synthesize and characterize a novel dual delivery system comprised of BSA-loaded in chitosan–dextran sulfate nanoparticulated carriers and mesenchymal stem cells that are encapsulated into alginate microparticles. The physicochemical and biological characteristics of this novel system, such as, morphology, release, swelling, and cytotoxicity were thoroughly characterized. The results obtained from confocal microscopy demonstrate that chitosan–dextran sulfate nanoparticles and cells are fully encapsulated within alginate microparticles, and spatially dispersed in the microparticle matrix. Moreover, scanning electron microscopy images revealed that these micro-sized carriers possess a rough surface, an important parameter that also promoted proper cell migration and adhesion. Notably, the incorporation of BSA in this duplex nano-micro delivery system extended its release profile throughout time, in comparison with microparticles alone, whilst not eliciting any cell damage. Taken together, these findings suggest that this dual carrier is a versatile delivery system with potential for a spatiotemporally controlled release of bioactive molecules and cells.
- New drug-eluting lenses to be applied as bandages after keratoprosthesis implantationPublication . Carreira, Ana; Ferreira, Paula; Ribeiro, MP.; Correia, Tiago R.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim Sobreira; Gil, MariaCorneal tissue is the most commonly transplanted tissue worldwide. This work aimed to develop a new drug-eluting contact lens that may be used as a bandage after keratoprosthesis. During this work, films were produced using poly(vinyl alcohol) (PVA) and chitosan (CS) crosslinked with glyoxal (GL). Vancomycin chlorhydrate (VA) was impregnated in these systems by soaking. Attenuated total reflectance – Fourier transform infrared spectroscopy was used to confirm crosslinking. The cytotoxic and drug release profile, hydrophilicity, thermal and biodegradation as well as swelling capacity of the samples were assessed through in vitro studies. PVA and PVA/CS films were obtained by crosslinking with GL. The films were transparent, flexible with smooth surfaces, hydrophilic and able to load and release vancomycin for more than 8 h. Biodegradation in artificial lachrymal fluid (ALF) with lysozyme at 37 °C showed that mass loss was higher for the samples containing CS. Also, the samples prepared with CS showed the formation of pores which were visualized by SEM. All samples revealed a biocompatible character after 24 h in contact with cornea endothelial cells. As a general conclusion it was possible to determine that the 70PVA/30CS film showed to combine the necessary features to prepare vancomycin-eluting contact lenses to prevent inflammation after corneal substitution.
- Recent advances on antimicrobial wound dressing: A reviewPublication . Simões, Déborah; Miguel, Sónia P.; Ribeiro, MP.; Coutinho, Paula Isabel Teixeira Gonçalves; Mendonça, António; Correia, Ilídio Joaquim SobreiraSkin and soft tissue infections (SSTIs) have high rates of morbidity and mortality associated. Despite the successful treatment of some SSTIs, those affecting the subcutaneous tissue, fascia, or muscle delay the healing process and can lead to life-threatening conditions. Therefore, more effective treatments are required to deal with such pathological situations. Recently, wound dressings loaded with antimicrobial agents emerged as viable options to reduce wound bacterial colonization and infection, in order to improve the healing process. In this review, an overview of the most prominent antibacterial agents incorporated in wound dressings along with their mode of action is provided. Furthermore, the recent advances in the therapeutic approaches used in the clinic and some future perspectives regarding antibacterial wound dressings are also discussed.
- Synthesis and characterization of a photocrosslinkable chitosan–gelatin hydrogel aimed for tissue regenerationPublication . Saraiva, Sofia Mendes; Miguel, Sónia P.; Ribeiro, MP.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraIn the area of tissue engineering different approaches have been studied, so far, for promoting regeneration or replacement of damaged tissues. Among the different materials developed, hydrogels, due to their biocompatibility and similarities with the native extracellular matrix, have emerged as suitable candidates for being used for different therapeutic purposes. Herein, photocrosslinkable hydrogels, composed by chitosan methacrylamide (ChMA) and gelatin methacrylamide (GelMA) were crosslinked by ultraviolet (UV) light, using Irgacue 2959 as photoinitiator. The morphological, physicochemical and biological properties of the hydrogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance. The obtained results demonstrated that the developed hydrogels possess suitable properties for being used as 3D constructs on several areas of tissue engineering. Furthermore, these properties may allow their future application as space filling agents or as delivery vehicles of bioactive molecules and cells.
- Thermoresponsive chitosan–agarose hydrogel for skin regenerationPublication . Miguel, Sónia P.; Ribeiro, MP.; Brancal, Hugo Gonçalo Monteiro Silva Aguiar; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraHealing enhancement and pain control are critical issues on wound management. So far, different wound dressings have been developed. Among them, hydrogels are the most applied. Herein, a thermoresponsive hydrogel was produced using chitosan (deacetylation degree 95%) and agarose. Hydrogel bactericidal activity, biocompatibility, morphology, porosity and wettability were characterized by confocal microscopy, MTS assay and SEM. The performance of the hydrogel in the wound healing process was evaluated through in vivo assays, during 21 days. The attained results revealed that hydrogel has a pore size (90–400 μm) compatible with cellular internalization and proliferation. A bactericidal activity was observed for hydrogels containing more than 188 μg/mL of chitosan. The improved healing and the lack of a reactive or a granulomatous inflammatory reaction in skin lesions treated with hydrogel demonstrate its suitability to be used in a near future as a wound dressing.