1,721,029 research outputs found
Cell encapsulation and delivery
No full textCell encapsulation is a technological procedure with the potential to treat a wide range of human diseases by replacing damaged or diseased cells. For this reason, in recent years, cell encapsulation and delivery for cellular therapy has been proposed for the treatment of different pathologies, including degenerative diseases, tumors, autoimmune diseases and trauma. Cellular therapy is generally based on two alternative concepts: the first one is based on the administration of free cells or aggregates, while in the second approach, cells are usually embedded or encapsulated in scaffolds. Generally, the first approach (defined as scaffold-free method) has the main inconvenience of likely evoking immune rejection of the implanted cells by the recipient. In addition, once implanted, the cells are not preserved by external exogenous stimuli, such as mechanical stimulation, and not surrounded by an appropriate environment promoting the regeneration of tissues and organs. On the contrary, the use of cell encapsulation methods allows immunoisolation of implanted cells, which increases their long-term in vivo survivability opening new avenues for targeted cell delivery. Moreover, encapsulation in specific scaffolds, typically made of polymers, provides the “appropriate” mechanical support for cell growth and tissue development
Rheological and functional characterization of new antiiflammatory delivery system designed for buccal administration
No full textAminated polysaccharide microspheres as DNA delivery systems
No full textThis article describes the production and characterization of cationic microparticles based on pullulan and starch for the delivery of nucleic acids. The microparticles were prepared by chemically cross-linkinking of a polymer solution dispersed in organic phase, followed by amination with N, N-diethyl-2-chloroethyl amine hydrochloride, or N-glycidyl-N,N-dimethyl-N-methylammonium chloride. The association of desoxyribonucleotide (DNA) with positively charged microparticles was determined. The association capacity and the affinity of microspheres for DNA were investigated as a function of type of polysaccharide, content and basicity of the amino groups. It was found that the both types of carriers synthetized display a high affinity for defibrotide due to the high porosity of polysaccharide microspheres (PMs). The in vitro release kinetics from microspheres showed an initial fast release of DNA (30 min) followed by slower release rate over 14 days. DNA release was influenced by the ionic strength of the receiving fluid. In addition, DNA release was slightly more rapid from pullulan than from starch complexes. DNA stability studies were performed by agarose gel, indicating no degradation even after 14 days. All the produced cationic microspheres were able to quantitatively load DNA. The release of DNA from PMs was strongly affected by the ionic strength of the receiving fluid. Finally, agarose gel electrophoresis of DNA released from microspheres indicated that no DNA degradation occurs even after 14 days of release from PMs
DoE Analysis of Approaches for Hydrogel Microbeads' Preparation by Millifluidic Methods
No full textHydrogel microbeads hold great promise for immune-protective cell transplants and in vitro studies. Millifluidic generation of hydrogel microbeads is a highly efficient and reproducible approach enabling a mass production. This paper illustrates the preparation and characterization of highly controlled and reproducible microbeads made by different types of hydrogel using millifluidic approaches. The optimization of the process was made by a design of experiments (DoE) approach. The microbeads' large-scale production can be potentially used for single cells or clusters encapsulation
Continuous-Flow Production of Liposomes with a Millireactor under Varying Fluidic Conditions
No full textContinuous-flow production of liposomes using microfluidic reactors has demonstrated advantages compared to batch methods, including greater control over liposome size and size distribution and reduced reliance on post-production processing steps. However, the use of microfluidic technology for the production of nanoscale vesicular systems (such as liposomes) has not been fully translated to industrial scale yet. This may be due to limitations of microfluidic-based reactors, such as low production rates, limited lifetimes, and high manufacturing costs. In this study, we investigated the potential of millimeter-scale flow reactors (or millireactors) with a serpentine-like architecture, as a scalable and cost-effective route to the production of nanoscale liposomes. The effects on liposome size of varying inlet flow rates, lipid type and concentration, storage conditions, and temperature were investigated. Liposome size (i.e., mean diameter) and size dispersity were characterised by dynamic light scattering (DLS); z-potential measurements and TEM imaging were also carried out on selected liposome batches. It was found that the lipid type and concentration, together with the inlet flow settings, had significant effects on the properties of the resultant liposome dispersion. Notably, the millifluidic reactor was able to generate liposomes with size and dispersity ranging from 54 to 272 nm, and from 0.04 to 0.52 respectively, at operating flow rates between 1 and 10 mL/min. Moreover, when compared to a batch ethanol-injection method, the millireactor generated liposomes with a more therapeutically relevant size and size dispersity
Friend erythroleukemic cells treated with aromatic polyamidines exhibiting antiproteinase activity: inhibition of cell growth is not associated with block of induced erythroid differentiation
No full textIn this paper we report the effects of aromatic poly amidines (TAPP-H, TAPB-H and DAPP-H) and their bromo-derivatives (TAPP-Br, TAPB-Br and DAPP-Br) on cell growth and erythroid differentiation of murine Friend erythroleukemic cells. These compounds are strong inhibitors of serine proteinases. The results obtained give evidence (a) for inhibition of cell proliferation by all the aromatic poly-amidines studied; (b) for stronger antiproliferative activity of the Br-derivatives; (c) for a lack of inhibition of globin mRNA accumulation and hemoglobin synthesis is uninduced cells as well as in Friend cells induced to erythroid differentiation by hexamethylenebisacetamide. These results suggest that this class of antiproliferative compounds exhibits differential effects on cell-cycle and differentiation specific genes. Thus, these aromatic poly-amidines could be used in experimental therapy without interfering with differentiative processes also when combined with differentiating agents
Analysis of the Diffusion Process by pH Indicator in Microfluidic Chips for Liposome Production
Full text linkIn recent years, the development of nano- and micro-particles has attracted considerable interest from researchers and enterprises, because of the potential utility of such particles as drug delivery vehicles. Amongst the different techniques employed for the production of nanoparticles, microfluidic-based methods have proven to be the most effective for controlling particle size and dispersity, and for achieving high encapsulation efficiency of bioactive compounds. In this study, we specifically focus on the production of liposomes, spherical vesicles formed by a lipid bilayer encapsulating an aqueous core. The formation of liposomes in microfluidic devices is often governed by diffusive mass transfer of chemical species at the liquid interface between a solvent (i.e., alcohol) and a non-solvent (i.e., water). In this work, we developed a new approach for the analysis of mixing processes within microfluidic devices. The method relies on the use of a pH indicator, and we demonstrate its utility by characterizing the transfer of ethanol and water within two different microfluidic architectures. Our approach represents an effective route to experimentally characterize diffusion and advection processes governing the formation of vesicular/micellar systems in microfluidics, and can also be employed to validate the results of numerical modelling
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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