Superhydrophobic platforms for the combinatorial analysis of biomaterials-cells interactions using arrays of 3D scaffolds with distinct mechanical and morphological properties

High-throughput studies of cells mechanotransduction are usually performed using 2D biomaterials. However, cells-extracellular matrix interactions in the body occur in 3D environment. By using cells entrapped in hydrogels, it is not easy to isolate the mechanical effect from the chemical cues of biomaterials. We used a cytocompatible and non-expensive platform based in the patterning of wettable spots in superhydrophobic surfaces to deposit porous biomaterials in these regions. Freeze-dried alginate/chitosan scaffolds were used to create an array of mechanical properties and porosities. Adaptation of dynamic mechanic analysis equipment allowed performing on-chip single scaffold analysis. Micro-computed tomography allowed acquir- ing data for whole chips simultaneously. Results were validated using individual scaffolds and single-formulation chips. A sub-array with combined modulus/porosity properties was selected. Fibronectin (Fn) in different concentration was adsorbed in the scaffolds, and fibroblasts and osteoblast-like cells were seeded. The independent study of variables influence in cell response was performed by image-based methods. In the absence of Fn fibroblasts did not respond to mechani- cal properties in the chip range. Osteoblast-like cells showed higher cell adhesion in stiffer substrates. The adsorption of Fn was studied qualita- tively by image methods. Results related with Fn amount and scaffolds’ mechanical properties were analyzed for each cell type.</p

Honey as a strategy to fight Candida tropicalis in mixed-biofilms with Pseudomonas aeruginosa

Fungal contaminations with Candida species are commonly responsible for several infections, especially when associated to bacteria. The therapeutic approach commonly used is being compromised due to microbial resistances of these microorganisms to antimicrobial agents, especially in biofilm. The use of honey as an antimicrobial agent has been emerging as a valuable solution and proving its potential in planktonic and in biofilm cells. This work aims to assess the effect of different honeys on biofilms of Candida tropicalis and Pseudomonas aeruginosa. The effect of Portuguese heather (PH) and manuka honeys on planktonic growth of Candida was initially evaluated by determination of the minimum inhibitory concentrations (MIC). Then, the same effect was evaluated in mixed biofilms, by colony-forming units numeration and fluorescence microscopy. The combinations of honey plus fluconazole and gentamicin were also tested. The results showed that the honeys tested enabled a great reduction of C. tropicalis, both in planktonic (12.5% and 25% of MIC for PH and manuka) and in biofilm. In polymicrobial biofilms, the use of PH and manuka honeys was revealed to be a promising choice and an alternative treatment, since they were able to reduce cells from both species. No synergistic effect was observed in antimicrobial combinations assays against polymicrobial biofilms.This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004), funded by the European Regional Development Fund under the scope ofNorte2020—Programa Operacional Regional do Norte and by PTDC/CVT-EPI/4008/2014 project.info:eu-repo/semantics/publishedVersio

Dendrimers in tissue engineering

Dendrimers are highly branched and multivalent, and monodispersive making them perfect candidates for a myriad of controlled drug delivery applications. Dendrimers possess many other advantages, such as the possibility of modulating surface chemistry and charge, and biodegradation rate and to be processed as scaffolds that can emulate natural extracellular matrices thus opening up unique applications in tissue engineering. The combination of dendrimers and other macromolecules (proteins and carbohydrates), as well as other traditional scaffold polymers, has led to the creation of hybrid scaffolds with new physical, mechanical, and biochemical properties. However, despite the widespread use of dendrimers in biomedical applications, their use in the fabrication of tissue engineering scaffolds remains some-how narrow. The most promising applications of dendritic macromolecules in TE area such as drug delivery strategies, cell differentiation and/or tissue regeneration, 3D/Dynamic platforms and ex vivo/in vivo testing are overviewed and discussed herein.JMO for the financial support provided under the program “Investigador FCT” (IF/01285/2015). MCR acknowledges the IET Institution of Engineering and Technology for the financial support provided under the IET Harvey Research Prize 2017. IMO thanks the financial support under the Norte2020 project (“NORTE-08-5369-FSE-000044”)

Investigation of Dendrimer-based nanoparticles cellular uptake and cell tracking in a semiautomated microfluidic platform

A microfluidic device such as Kima Pump and Vena8 biochip is able to realize functions that are not easily imaginable in conventional biological analysis, such as highly parallel, sophisticated high-throughput analysis and single-cell analysis in a well-defined manner [1]. Cancer cell tracking within the microfluidic model will be achieved by grafting fluorescent label probe Fluorescein-5(6)-isothiocyanate (FITC) to dendrimer nanoparticles allowing cell visualization by immunofluorescent staining followed by fluorescence microscopy. In this study, synthesis and physicochemical characterization of Carboxymethyl-chitosan/poly(amidoamine) dendrimer nanoparticles (CMCht/PAMAM NPâ s) were performed[2].  Several cancer cell lines such as a HeLA (cervical carcinoma cell line), HTTC-116 (Colon Carcinoma) and Glioblastome cell line (GBM) were exposed to different concentrations of CMCht/PAMAM dendrimer nanoparticles over a period of 7d. After finding the adequate NP concentration, the internalization efficiency was tested, as well as cellular trafficking, in static and dynamic conditions (Kima Pump bioreactor).Portuguese Foundation for Science and Technology (FCT) through the project PEst­C/SAU/LA0026/20

Rheological and mechanical properties of acellular and cellladen methacrylated gellan gum hydrogels

Tissue engineered hydrogels hold great potential as nucleus pulposus substitutes (NP), as they promote intervertebral disc (IVD) regeneration and re-establish its original function. But, the key to their success in future clinical applications greatly depends on its ability to replicate the native 3D micro-environment and circumvent their limitation in terms of mechanical performance. In the present study, we investigated the rheological/mechanical properties of both ionic- (iGG-MA) and photo-crosslinked methacrylated gellan gum (phGG-MA) hydrogels. Steady shear analysis, injectability and confined compression stress-relaxation tests were carried out. The injectability of the reactive solutions employed for the preparation of iGG-MA and phGG-MA hydrogels was firstly studied, then the zero-strain compressive modulus and permeability of the acellular hydrogels were evaluated.In addition, human intervertebral disc (hIVD) cells encapsulated in both iGG-MA and phGG-MA hydrogels were cultured in vitro, and its mechanical properties also investigated under dynamic mechanical analysis at 37ºC and pH 7.4. After 21 d of culturing, hIVD cells were alive (Calcein AM) and the E’ of ionic-crosslinked hydrogels and photo-crosslinked was higher than that observed for acellular hydrogels. Our study suggests that methacrylated gellan gum hydrogels present promising mechanical and biological performance as hIVD cells were producing extracellular matrix

IL-7R-mediated signaling in T-cell acute lymphoblastic leukemia: an update

© 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/)Interleukin 7 (IL-7) and its receptor (IL-7R, a heterodimer of IL-7Rα and γc) are essential for normal lymphoid development. In their absence, severe combined immunodeficiency occurs. By contrast, excessive IL-7/IL-7R-mediated signaling can drive lymphoid leukemia development, disease acceleration and resistance to chemotherapy. IL-7 and IL-7R activate three main pathways: STAT5, PI3K/Akt/mTOR and MEK/Erk, ultimately leading to the promotion of leukemia cell viability, cell cycle progression and growth. However, the contribution of each of these pathways towards particular functional outcomes is still not completely known and appears to differ between normal and malignant states. For example, IL-7 upregulates Bcl-2 in a PI3K/Akt/mTOR-dependent and STAT5-independent manner in T-ALL cells. This is a 'symmetric image' of what apparently happens in normal lymphoid cells, where PI3K/Akt/mTOR does not impact on Bcl-2 and regulates proliferation rather than survival. In this review, we provide an updated summary of the knowledge on IL-7/IL-7R-mediated signaling in the context of cancer, focusing mainly on T-cell acute lymphoblastic leukemia, where this axis has been more extensively studied.Publication costs were supported by LISBOA-01-0145-FEDER-007391, project cofunded by FEDER, through POR Lisboa2020 Programa Operacional Regional de Lisboa, PORTUGAL 2020, and Fundação para a Ciência e a Tecnologia (FCT, Portugal). The research work in JTB's lab related to the present review was supported by the grants FAPESP/20015/2014 and PTDC/MEC-HEM/31588/2017, from FCT; and by the consolidator grant ERC CoG-648455 from the European Research Council, under the European Union's Horizon 2020 research and innovation programme. JTB is an FCT investigator (consolidator). MLO is a LisbonBioMed PhD student and received a fellowship from FCT. PA received a PhD fellowship from the EU Marie Sklodowska-Curie ITN Protein Conjugates.info:eu-repo/semantics/publishedVersio

Role of extracellular DNA in Candida albicans biofilms

DNA has been described as a structural component of the extracellular matrix in bacterial biofilms. However, in Candida albicans there is a scarce knowledge concerning the contribution of extracellular DNA (ecDNA) to biofilm matrix and overall structure. The main objective of this work was to examine the effect of Deoxyribonuclease I (DNase) treatment and the addition of exogenous DNA on C. albicans biofilm as indicators of the role of ecDNA in biofilm structure and development. Using a rapid and robust method (96-well plate model), the effect of DNase (ranging from 0.02 to 2 mg/ml) and exogenous DNA (ranging from 10 to 2560 ng/ml) on biofilm formation was examined at different stages of C. albicans biofilm development. Specifically, standardized cell suspensions (100 μl of 1 × 106 cells/ml in RPMI) were inoculated into 96-well microtitre plates and incubated for 0, 1, 2 and 24 h at 37°C under static conditions. At 0-h (preincubation), DNase or exogenous DNA were added to the standardized suspension. At 1-, 2- and 24-h of incubation the medium was removed and adhered cells were washed with PBS. DNase or exogenous DNA working solutions were then added to C. albicans sessile cells. The plates were incubated at 37 °C for additional 24 h. Biofilm biomass was evaluated by crystal violet assay. The results of these experiments showed that DNase did not exhibit major effects on C. albicans adherent cells at early time points of biofilm development. However, DNase showed a general biomass reduction on C. albicans preformed biofilms, with the reduction of absorbance at 550 nm compared with the control at DNase concentrations higher than 0.03 mg/ml. The addition of exogenous DNA to C. albicans adhered cell populations did not affect further biofilm development. In contrast, addition of exogenous DNA, at concentrations higher than 160 ng/ml to preformed biofilms led to an increase in biofilm biomass, as indicated by the higher levels of crystal violet readings compared with control biofilms. Thus, we present evidence of the role of ecDNA in C. albicans biofilm structure, consistent with ecDNA being a key element of the ECM in mature C. albicans biofilms and playing a predominant role in biofilm structural integrity and maintenance

Novel strategies to fight Candida infections: natural honey

Poster apresentado no "CEB Annual Meeting", em Braga, Portugal, 2017The incidence of Candida infections (Candidosis) has increased remarkably in the last years, being attributed to the rise in the elderly population, the increasing number of immunocompromised patients, and the widespread use of indwelling medical devices. Candida albicans remains as the most prevalent species of these infections, but a clear rise in the proportion of non-Candida albicans Candida (NCAC) species has been noted. These species have an inherent level of resistance to certain antifungal agents higher than C. albicans though their virulence factors are much less understood. A major virulence factor is the ability to adhere and to form biofilms in medical devices and host tissues, because of a higher tolerance to antifungal therapy. Consequently, there is an urgent need to develop new strategies to fight these infections. Natural compounds are attracting increased interest in this field, among which honey. AIM: To evaluate honey as a novel strategy to fight C. tropicalis infections.This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Natural honey to fight Candida infections

Eurobiofilms 2017 - 5th European Congress on Microbial BiofilmsThe incidence of Candida infections (Candidosis) has increased remarkably in the last years, being attributed to the rise in the elderly population, the increasing number of immunocompromised patients, and the widespread use of indwelling medical devices. Candida albicans remains as the most prevalent species of these infections, but a clear rise in the proportion of non-Candida albicans Candida (NCAC) species has been noted. These species have an inherent level of resistance to certain antifungal agents higher than C. albicans though their virulence factors are much less understood. A major virulence factor is the ability to adhere and to form biofilms in medical devices and host tissues, because of a higher tolerance to antifungal therapy. Consequently, there is an urgent need to develop new strategies to fight these infections. Natural compounds are attracting increased interest in this field, among which honey. AIM: To evaluate honey as a novel strategy to fight C. tropicalis infections.This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Evaluating biomaterial-and microfluidic-based 3D tumor models

Cancer is a major cause of morbidity and mortality worldwide, with a disease burden estimated to increase in the coming decades. Disease heterogeneity and limited information on cancer biology and disease mechanisms are aspects that 2D cell cultures fail to address. We review the current "state-of-the-art" in 3D Tissue Engineering (TE) models developed for and used in cancer research. Scaffold-based TE models and microfluidics, are assessed for their potential to fill the gap between 2D models and clinical application. Recent advances in combining the principles of 3D TE models and microfluidics are discussed, with a special focus on biomaterials and the most promising chip-based 3D models.The authors would like to thank the European Union's Seventh Framework Program (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and QREN (ON.2 - NORTE-01-0124-FEDER-000016) co-financed by North Portugal Regional Operational Program (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) for providing financial support to this project. The FCT distinction attributed to J.M.O. under the Investigator FCT program (IF/00423/2012) Is also greatly acknowledged