Assessment of Migration of Human MSCs through Fibrin Hydrogels as a Tool for Formulation Optimisation

Control of cell migration is fundamental to the performance of materials for cell delivery, as for cells to provide any therapeutic effect, they must migrate out from the delivery material. Here the influence of fibrinogen concentration on the migration of encapsulated human mesenchymal stem cells (hMSCs) from a cell spheroid through fibrin hydrogels is tracked over time. Fibrin was chosen as a model material as it is routinely employed as a haemostatic agent and more recently has been applied as a localised delivery vehicle for potential therapeutic cell populations. The hydrogels consisted of 5 U/mL thrombin and between 5 and 50 mg/mL fibrinogen. Microstructural and viscoelastic properties of different compositions were evaluated using SEM and rheometry. Increasing the fibrinogen concentration resulted in a visibly denser matrix with smaller pores and higher stiffness. hMSCs dispersed within the fibrin gels maintained cell viability post-encapsulation, however, the migration of cells from an encapsulated spheroid revealed that denser fibrin matrices inhibit cell migration. This study provides the first quantitative study on the influence of fibrinogen concentration on 3D hMSC migration within fibrin gels, which can be used to guide material selection for scaffold design in tissue engineering and for the clinical application of fibrin sealants

Influence of PCL and PHBV on PLLA Thermal and Mechanical Properties in Binary and Ternary Polymer Blends

PLLA, PCL and PHBV are aliphatic polyesters which have been researched and used in a wide range of medical devices, and all three have advantages and disadvantages for specific applications. Blending of these materials is an attractive way to make a material which overcomes the limitations of the individual polymers. Both PCL and PHBV have been evaluated in polymer blends with PLLA in order to provide enhanced properties for specific applications. This paper explores the use of PCL and PHBV together with PLLA in ternary blends with assessment of the thermal, mechanical and processing properties of the resultant polymer blends, with the aim of producing new biomaterials for orthopaedic applications. DSC characterisation is used to demonstrate that the materials can be effectively blended. Blending PCL and PHBV in concentrations of 5-10% with PLLA produces materials with average modulus improved by up to 25%, average strength improved by up to 50% and average elongation at break improved by 4000%, depending on the concentrations of each polymer used. PHBV impacts most on the modulus and strength of the blends, whilst PCL has a greater impact on creep behaviour and viscosity. Blending PCL and PHBV with PLLA offers an effective approach to the development of new polyester-based biomaterials with combinations of mechanical properties which cannot be provided by any of the materials individually

Insight into halloysite nanotubes-loaded gellan gum hydrogels for soft tissue engineering applications

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Impact of heterogeneously crosslinked calcium alginate networks on the encapsulation of β-carotene-loaded beads

This study investigated the impact of heterogeneity of crosslinking on a range of physical and mechanical properties of calcium alginate networks formed via external gelation with 0.25–2% sodium alginate and 2.5 and 5% CaCl2. Crosslinking in films with 1–2% alginate was highly heterogeneous, as indicated by their lower calcium content (35–7 mg Ca·g alginate−1) and apparent solubility (5–6%). Overall, films with 1–2% alginate showed higher resistance (tensile strength = 51–147 MPa) but lower elasticity (Elastic Modulus = 2136–10,079 MPa) than other samples more homogeneous in nature (0.5% alginate, Elastic Modulus = 1918 MPa). Beads with 0.5% alginate prevented the degradation of β-carotene 1.5 times more efficiently than 1% beads (5% CaCl2) at any of the storage temperatures studied. Therefore, it was postulated that calcium alginate networks crosslinked to a greater extent and in a more homogeneous manner showed better mechanical performance and barrier properties for encapsulation applications

Impact of post-harvest treatments on physicochemical and sensory characteristics of coffee beans in Huila, Colombia

[EN] Post-harvest methods applied on coffee cherries processing impact the resulting physicochemical characteristics, and the roasting modulates the beans composition, influencing their sensory analysis. Thus, this work studied the influence of different post-harvest methods (dry, wet and semi-dry) and roasting intensity on the physicochemical characteristics, antioxidant capacity (DPPH, ABTS) and bioactive compounds content of coffee (C. arabica L. var. Colombia) samples. Additionally, sensory attributes were determined. The results showed that the degree of roasting modified strongly all the investigated parameters, mainly colour, antioxidant capacity and 5-hydroxymethylfurfural content. Furthermore, the Principal Components Analysis (PCA) explained 87.4 % of the variability of the samples and the results of the antioxidants and hydroxymethylfurfural are related to the roasting degree, while the pH and the chlomgenic acids content allow discriminating the green samples. Finally, the post-harvest methods determined the sensory profile, resulting in coffees with highly differentiated characteristics and classified as "Specialty coffee.The authors acknowledge the support of Universidad Surcolombiana for beans processing and roasting (USCO-VIPS-3050) .Cortés-Macías, ET.; Fuentes López, C.; Gentile, P.; Girón Hernández, J.; Fuentes López, A. (2022). Impact of post-harvest treatments on physicochemical and sensory characteristics of coffee beans in Huila, Colombia. Postharvest Biology and Technology. 187:1-9. https://doi.org/10.1016/j.postharvbio.2022.1118521918

Image-Based Three-Dimensional Analysis to Characterize the Texture of Porous Scaffolds

The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture

Conceptual design and development of a progressive cavity pump for extrusion-based additive manufacturing applications

The present study aimed to develop a low-cost, scalable, easy-to-clean extrusion system based on the progressive cavity pump (PCP) principle for extrusion-based additive manufacturing, with a specific focus on bioprinting. Therefore, the study proposes a spiral development model to achieve a novel PCP with the help of additive manufacturing (AM). An application programming interface was developed to enable quick design iterations. User requirements were determined through literature research, a user questionnaire and interviews. Consequently, three novel PCP concepts were designed and developed using the developed model, and the proof of concept for the selected PCP design was presented

Bioprinted High-Cell-Density Laminar Scaffolds Stimulate Extracellular Matrix Production in Osteochondral Co-Cultures

Many tissues have a laminar structure, but there are limited technologies for establishing laminar co-cultures for in vitro testing. Here, we demonstrate that collagen–alginate–fibrin (CAF) hydrogel scaffolds produced using the reactive jet impingement bioprinting technique can produce osteochondral laminar co-cultures with well-defined interfaces between cell types and high cell densities to support cell–cell interaction across the interfaces. The influence of cell density and the presence of the two cell types on the production of extracellular matrix (ECM) and the emergent mechanical properties of gels is investigated using IHC, ELISA, gel mass, and the compression modulus. The results indicate that high-cell-density cultures and co-cultures with these specific cell types produce greater levels of ECM and a more biomimetic in vitro culture than low-cell-density cultures. In laminar scaffolds produced using TC28a2 chondrocytes and SaoS-2 osteoblasts, both cell density and the presence of the two cell types enhance ECM production and the mechanical properties of the cultures, presenting a promising approach for the production of more biomimetic in vitro models