Browsing by Author "Sousa, A."
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- Biomechanical performance of hybrid electrospun structures for skin regenerationPublication . Dias, J. R.; Baptista-Silva, S.; Sousa, A.; Oliveira, A. L.; Bártolo, P. J.; Granja, P. L.Wound dressings made by electrospun nanofibers have been demonstrating great potential to regenerate skin tissue as compared to the conventional membrane products available in the market. Until today most of the developed dressings have only demonstrated the capability to regenerate the dermis or epidermis. In this study we propose new hybrid electrospun meshes combining polycaprolactone and gelatin. Several approaches, multilayer, coating and blend were stablished to investigate the most appropriate hybrid structure with potential to promote skin regeneration in its full thickness. The structures were evaluated in terms of physico-chemical properties (porosity, water vapor permeability, contact angle and swelling degree) and according to its mechanical and biological performance. Multilayer and blend structures demonstrated to fit most of native skin requirements. However, looking to all the performed characterization we considered multilayer as the most promising hybrid structures, due its high porosity which contributed to an ideal water vapor permeability rate and good mechanical and biological properties. Based on this multilayer structure is a promisor wound dressing.
- In situ crosslinked electrospun gelatin nanofibers for skin regenerationPublication . Dias, J. R.; Baptista-Silva, S.; Oliveira, C. M. T. de; Sousa, A.; Oliveira, Ana L.; Bártolo, P. J.; Granja, P. L.Due to its intrinsic similarity to the extracellular matrix, gelatin electrospun nanofibrous meshes are promising scaffold structures for wound dressings and tissue engineering applications. However, gelatin is water soluble and presents poor mechanical properties, which generally constitute relevant limitations to its applicability. In this work, gelatin was in situ crosslinked with 1,4-butanediol diglycidyl ether (BDDGE) at different concentrations (2, 4 and 6 wt%) and incubation time-points (24, 48 and 72 h) at 37 °C. The physico-chemical and biological properties of BDDGE-crosslinked electrospun gelatin meshes were investigated. Results show that by changing the BDDGE concentration it is possible to produce nanofibers crosslinked in situ with well-defined morphology and modulate fiber size and mechanical properties. Crosslinked gelatin meshes show no toxicity towards fibroblasts, stimulating their adhesion, proliferation and synthesis of new extracellular matrix, thereby indicating the potential of this strategy for skin tissue engineering.
- Influência de membranas de policaprolactona na remodelação celular de um modelo animal de úlceras de pé diabéticoPublication . Gojon, F.; Sousa, A.; Rocha, A. C.; Sousa-Mendes, C.; Rodrigues, I.; Soares, R.; Fernandes, R.; Costa, R.
- Unlocking the potential of decellularized rabbit dermal matrices for advancing skin regenerationPublication . Rosadas, M.; Sousa, T.; Silva, I. V.; Sousa, A.; Ribeiro, V. P.; Oliveira, A. L.Purpose Burn wounds represent a significant challenge in medical care, particularly due to the complexity of dermal reconstruction. The use of autologous grafts as substitutes is the standard option, however, it may not be suitable to deep and extensive burns (1). An alternative approach involves employing artificial collagen-based dermal substitutes, which do not meet the full requirements of the dermis extracellular matrix (ECM) in terms of biochemical composition and architectural features (2). Thus, skin xenografts have emerged as a suitable option involving the need for decellularization to remove the immunogenic material preserved ECM for skin regeneration (3). Focused on these valences, this study describes for the first time a refining protocol for decellularizing rabbit dermis, a valuable agro-food by-product which exceeds 5000 skins/day. The presented approach allowed to obtain highly preserved decellularized dermal matrices with microarchitecture and biochemical properties similar to that of human dermis. Methods Rabbit skins by-product were processed at Cortadoria Nacional de Pêlo S.A., following a set of pioneer methodologies involving chemical, enzymatic and mechanical processing. The obtained purified rabbit dermis was further processed through selected chemical decellularization agents (SDS and SDC) with varying exposure periods, to achieve a fast and complete decellularization process with a minimum impact to dermal matrices’ microarchitecture, mechanical properties and biochemical composition. The impact of the processing methods and decellularization agents on matrix preservation was examined by morphological analysis (SEM), swelling properties and tensile mechanical behavior, compared to that of human skin. The cellular content and decellularization effectiveness were confirmed by histological analysis and DNA quantification. Human dermal fibroblast (hDFs) were used for testing the in vitro cytocompatibility of the preserved decellularized rabbit dermal matrices (dRDMs). Further characterizations, including GAGs and collagen quantification are ongoing to confirm the dRDM preservation and a newly-formed ECM the seeded cells. Results The obtained results indicate that the applied methods and reagents at different pHs influence collagen matrix conformation, affecting the swelling capability and fluid interaction. Morphological analysis revealed different surface properties at the rabbit dermis, showing a flat epidermal-contacting surface with pores resulting from fur removal and another fibrous hypodermis-contacting surface, as well as different topographical effects depending on the decellularization agents and exposure time. Mechanical properties showed different impacts of the decellularization agents on collagen content of the dRDMs but with a good overall integrity throughout rabbit dermis processing. DNA quantification confirmed different decellularization efficiencies (<50 ng/mg dry weight) depending on the processing stage and decellularization agents. From in vitro characterization it was observed that the obtained dRDMs supported hDFs adhesion and proliferation up to 7 days of culture. Conclusions This study marks the first demonstration of successfully clean chemical methods for rabbit dermis processing and decellularization, preserving ECM components and yielding high-quality matrices with superior biological, structural and biomechanical properties to cover large areas of the human body while promoting skin regeneration.