1,721,028 research outputs found
High-throughput microfluidic platform for 3D cultures of mesenchymal stem cells
No full textThe design of innovative tools for generating physiologically relevant three-dimensional (3D) in vitro models has been recently recognized as a fundamental step to study cell responses and long-term tissue functionalities thanks to its ability to recapitulate the complexity and the dimensional scale of the cellular microenvironment, while directly integrating high-throughput and automatic screening capabilities. This chapter addresses the development of a poly(dimethylsiloxane)-based microfluidic platform to (1) generate and culture 3D cellular microaggregates under continuous flow perfusion while (2) conditioning them with different combinations/concentrations of soluble factors (i.e., growth factors, morphogens or drug molecules), in a high-throughput fashion. The proposed microfluidic system thus represents a promising tool for establishing innovative high-throughput models for drug screening, investigation of tissues morphogenesis, and optimization of tissue engineering protocols
VA-086 methacrylate gelatine photopolymerizable hydrogels: A parametric study for highly biocompatible 3D cell embedding
Full text linkThe ability to replicate in vitro the native extracellular matrix (ECM) features and to control the three-dimensional (3D) cell organization plays a fundamental role in obtaining functional engineered bioconstructs. In tissue engineering (TE) applications, hydrogels have been successfully implied as biomatrices for 3D cell embedding, exhibiting high similarities to the natural ECM and holding easily tunable mechanical properties. In the present study, we characterized a promising photocrosslinking process to generate cell-laden methacrylate gelatin (GelMA) hydrogels in the presence of VA-086 photoinitiator using a ultraviolet LED source. We investigated the influence of prepolymer concentration and light irradiance on mechanical and biomimetic properties of resulting hydrogels. In details, the increasing of gelatin concentration resulted in enhanced rheological properties and shorter polymerization time. We then defined and validated a reliable photopolymerization protocol for cell embedding (1.5% VA-086, LED 2 mW/cm2) within GelMA hydrogels, which demonstrated to support bone marrow stromal cells viability when cultured up to 7 days. Moreover, we showed how different mechanical properties, derived from different crosslinking parameters, strongly influence cell behavior. In conclusion, this protocol can be considered a versatile tool to obtain biocompatible cell-laden hydrogels with properties easily adaptable for different TE applications
A new microfluidic platform for the highly reproducible preparation of non-viral gene delivery complexes
Full text linkTransfection describes the delivery of exogenous nucleic acids (NAs) to cells utilizing non-viral means. In the last few decades, scientists have been doing their utmost to design ever more effective transfection reagents. These are eventually mixed with NAs to give rise to gene delivery complexes, which must undergo characterization, testing, and further refinement through the sequential reiteration of these steps. Unfortunately, although microfluidics offers distinct advantages over the canonical approaches to preparing particles, the systems available do not address the most frequent and practical quest for the simultaneous generation of multiple polymer-to-NA ratios (N/Ps). Herein, we developed a user-friendly microfluidic cartridge to repeatably prepare non-viral gene delivery particles and screen across a range of seven N/Ps at once or significant volumes of polyplexes at a given N/P. The microchip is equipped with a chaotic serial dilution generator for the automatic linear dilution of the polymer to the downstream area, which encompasses the NA divider to dispense equal amounts of DNA to the mixing area, enabling the formation of particles at seven N/Ps eventually collected in individual built-in tanks. This is the first example of a stand-alone microfluidic cartridge for the fast and repeatable preparation of non-viral gene delivery complexes at different N/Ps and their storage
Development and validation of a high-throughput microfluidic platform for cell culture and non-viral gene delivery
No full textUn fiume di variazioni benefiche: l’evoluzione teistica di Asa Gray
No full textThis paper presents the american
botanist Asa Gray’s «theistic
evolution», founded on the idea of
the compatibility between natural
selection and natural theology, as
it emerges from his writings on the
darwinian themes and from his
correspondence with Darwin. To the
«orthodox presbyterian» Gray, the
variations on which natural
selection works, whose origin Darwin
defined as «accidental», have been
led «along beneficial lines» by God,
the author of the design of nature
Gelatin hydrogels via thiol-ene chemistry
No full textA new hydrogel, totally based on gelatin has been synthesized by cross-linking thiolated gelatin with pentenoyl gelatin, via thiol-ene click chemistry. Preliminary cytocompatibility assays with hBMSC showed good cell compatibility
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
Generation of functional cardiac microtissues in a beating heart-on-a-chip
No full textWith the increasing attention on cardiovascular disorders and the current inability of pre-clinical models to accurately predict human physiology, the need for advanced and reliable heart in vitro models is paramount. Microfabrication technologies provide potential solutions in the organs-on-chip systems: microengineered devices where cell cultures can be hosted and cultured to develop three-dimensional models or microtissues with high similarity to human physiology. We here described the fabrication and operation procedures for a beating heart-on-a-chip. The device features a culture region for a 3D cardiac microtissue and a system for applying tuned mechanical stimulation during culture to improve cardiac development. We additionally describe procedures for characterizing tissue maturation via immunofluorescence and functional evaluations of microtissue contractility
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