Search

Chronic kidney disease (CKD) is a major healthcare burden that takes a toll on the quality of life of many patients. Emerging evidence indicates that a substantial proportion of these patients carry a genetic defect that contributes to their disease. Any effort to reduce the percentage of patients with a diagnosis of nephropathy heading towards kidney replacement therapies should therefore be encouraged. Besides early genetic screenings and registries, in vitro systems that mimic the complexity and pathophysiological aspects of the disease could advance the screening for targeted and personalized therapies. In this regard, the use of patient-derived cell lines, as well as the generation of disease-specific cell lines via gene editing and stem cell technologies, have significantly improved our understanding of the molecular mechanisms underlying inherited kidney diseases. Furthermore, organs-on-chip technology holds great potential as it can emulate tissue and organ functions that are not found in other, more simple, in vitro models. The personalized nature of the chips, together with physiologically relevant read-outs, provide new opportunities for patient-specific assessment, as well as personalized strategies for treatment. In this review, we summarize the major kidney-on-chip (KOC) configurations and present the most recent studies on the in vitro representation of genetic kidney diseases using KOC-driven strategies., Author(s): Marta G. Valverde [sup.1] , João Faria [sup.1] , Elena Sendino Garví [sup.1] , Manoe J. Janssen [sup.1] , Rosalinde Masereeuw [sup.1] , Silvia M. Mihaila [sup.1] Author Affiliations: [...]

Recent achievements in the area oftissue engineering (TE) haveenabled the development of three-dimensional (3D) cell-laden hydrogelsas in vitro platforms that closely mimic the 3D scenario found innative tissues. These platforms are extensively used to evaluate cellularbehavior, cell–cell interactions, and tissue-like formationin highly defined settings. In this study, we propose a scalable andflexible 3D system based on microsized hydrogel fibers that mightbe used as building blocks for the establishment of 3D hydrogel constructsfor vascularized bone TE applications. For this purpose, chitosan(CHT) coated κ-carrageenan (κ-CA) microfibers were developedusing a two-step procedure involving ionotropic gelation (for thefiber formation) of κ-CA and its polyelectrolyte complexationwith CHT (for the enhancement of fiber stability). The performanceof the obtained fibers was assessed regarding their swelling and stabilityprofiles, as well as their ability to carry and, subsequently, promotethe outward release of microvascular-like endothelial cells (ECs),without compromising their viability and phenotype. Finally, the possibilityof assembling and integrating these cell-laden fibers within a 3Dhydrogel matrix containing osteoblast-like cells was evaluated. Overall,the obtained results demonstrate the suitability of the microsizedκ-CA fibers to carry and deliver phenotypically apt microvascular-likeECs. Furthermore, it is shown that it is possible to assemble thesecell-laden microsized fibers into 3D heterotypic hydrogels constructs.This in vitro 3D platform provides a versatile approach to investigatethe interactions between multiple cell types in controlled settings,which may open up novel 3D in vitro culture techniques to better mimicthe complexity of tissues. [ABSTRACT FROM AUTHOR]

The construction of scaffolds and subsequent incorporation of cells and biologics have been widely investigated to regenerate damaged tissues. Scaffolds act as a template to guide tissue formation, and their characteristics have a considerable impact on the regenerative process. Whereas many technologies exist to induce specific two-dimensional (2D) morphologies into biomaterials, the introduction of three-dimensional (3D) micromorphologies into individual pore walls of scaffolds produced from biological molecules such as collagen poses a challenge. We here report the use of dicarboxylic acids to induce specific micromorphologies in collagen scaffolds and evaluate their effect on cellular migration and differentiation. Insoluble type I collagen fibrils were suspended in monocarboxylic and dicarboxylic acids of different concentrations, and unidirectional and random pore scaffolds were constructed by freezing and lyophilization. The application of various acids and concentrations resulted in variations in 3D micromorphologies, including wall structure, wall thickness, and pore size. The use of dicarboxylic acids resulted in acid-specific micromorphologies, whereas monocarboxylic acids did not. Dicarboxylic acids with an odd or even number of C-atoms resulted in frayed/fibrillar or smooth wall structures, respectively, with varying appearances. The formation of micromorphologies was concentration-dependent. In vitro analysis indicated the cytocompatibility of scaffolds, and micromorphology-related cell behavior was indicated by enhanced myosin staining and myosin heavy chain gene expression for C2C12 myoblasts cultured on scaffolds with frayedlike micromorphologies compared to those with smooth micromorphologies. In conclusion, porous collagen scaffolds with various intrawall 3D micromorphologies can be constructed by application of dicarboxylic acids, superimposing the second level of morphology to the overall scaffold structure. Acid crystal formation is key to the specific micromorphologies observed and can be explained by the odd/even theory for dicarboxylic acids. Scaffolds with a 3D micrometer-defined topography may be used as a screening platform to select optimal substrates for the regeneration of specific tissues., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Bone formation relies on complex processes that require well-orchestrated interactions between several cell types, such as bone-forming cells (osteoblasts, OBs) and endothelial cells (ECs). Their co-culture has been proved relevant to mimicking specific features of the bone niche. Here we propose the co-culture of microvascular-like ECs and pre-OBs, both derived from the SSEA-4 + cell subpopulation from the stromal vascular fraction of human adipose tissue (SSEA-4 + hASCs), to define the conditions in which cells synergistically communicate to support the full differentiation of pre-OBs and maintenance of the EC phenotype. Co-cultures of different ratios of the two cell types were established and maintained for up to 21 days in standard endothelial maintenance (ENDO) and osteogenic differentiation (OST) media, as well as in a mixture of these (MIX). The osteogenic maturation of pre-OBs (ALP activity, OPN and OCN expression, calcium deposition), the evolution of EC numbers (CD31 + cells) and maintenance of the endothelial phenotype (CD31 and vWF expression, LDL uptake) were assessed throughout the culture time as a function of cell ratio and culture media. The results obtained demonstrate that EC number has a significant effect on the osteogenic differentiation of pre-OBs, depending on the medium used. While in ENDO medium the osteogenic differentiation was not observed, in the OST and MIX media it was attained at similar levels, except for the co-culture with a higher number of ECs in MIX medium. These findings demonstrate that the use of SSEA-4 + hASCs as a single-cell source is promising to attain 3D bone-like models with the potential to promote vascularized bone tissue regeneration. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)