Alginate hydrogels as synthetic extracellular matrix materials
TL;DR: Alginate may prove to be an ideal material with which to confer specific cellular interactive properties, potentially allowing for the control of long-term gene expression of cells within these matrices.
About: This article is published in Biomaterials.The article was published on 1999-01-01. It has received 2116 citations till now. The article focuses on the topics: Self-healing hydrogels & Cell adhesion.
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TL;DR: This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers.
5,372 citations
TL;DR: Hydrogels are an appealing scaffold material because they are structurally similar to the extracellular matrix of many tissues, can often be processed under relatively mild conditions, and may be delivered in a minimally invasive manner.
4,573 citations
Cites background or methods from "Alginate hydrogels as synthetic ext..."
...A common approach to design a highly specific adhesive surface is to covalently couple an entire ECM protein [21,88] or peptide sequences capable of binding to cellular receptors [15,88,91] to the polymer....
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...Most cell types are able to bind to RGD, thus both alginate [69,91] and PEG [15,92,93] have been modified with this peptide to promote cellular adhesion (Fig....
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...Effect of coupling RGD to alginate on cell adhesion: (a) unmodified alginate seeded with C2C12 myoblasts (reprinted from [91] with permission, copyright Elsevier Sciences Ltd), (b) rat-derived calvarial osteoblasts on G4RGDY-modified alginate (reprinted from [69] with permission, copyright IARD), and (c) C2C12 myoblasts on G4RGDY-modified alginate (reprinted from [91] with permission, copyright Elsevier Sciences Ltd)....
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...Note: Image of rat-derived calvarial osteoblasts seeded on unmodified alginate not shown because no adhesion occurred [91], as in (a) with C2C12 myoblasts....
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4,511 citations
TL;DR: This work highlights recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for biomedical and biological applications and shows how such systems' intelligent behavior can be used in sensors, microarrays, and imaging.
Abstract: Hydrophilic polymers are the center of research emphasis in nanotechnology because of their perceived “intelligence”. They can be used as thin films, scaffolds, or nanoparticles in a wide range of biomedical and biological applications. Here we highlight recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for these applications. Natural, biohybrid, and synthetic hydrophilic polymers and hydrogels are analyzed and their thermodynamic responses are discussed. In addition, examples of the use of hydrogels for various therapeutic applications are given. We show how such systems’ intelligent behavior can be used in sensors, microarrays, and imaging. Finally, we outline challenges for the future in integrating hydrogels into biomedical applications.
3,524 citations
TL;DR: In this paper, pH-induced self-assembly of a peptide-amphiphile was used to make a nanostructured fibrous scaffold reminiscent of extracellular matrix.
Abstract: We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.
3,125 citations
References
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TL;DR: The ability to switch hepatocytes from differentiation to growth is not limited to a single ECM molecule, a distinct three dimensional ECM geometry, or due to alteration of cell‐cell interactions, rather, the regulatory signals conveyed by immobilized ECM molecules depend on the density at which they are presented and thus, on their ability to either prohibit or support cell spreading.
Abstract: Studies were carried out to analyze how different extracellular matrix (ECM) molecules regulate hepatocyte growth and differentiation. Freshly isolated rat hepatocytes were cultured on non-adhesive plastic dishes that were pre-coated with defined densities of either laminin, fibronectin, type I collagen, or type IV collagen. Sparse cell plating densities were used to minimize cell-cell contact formation and all studies were carried out in chemically defined medium that contained a saturating amount of soluble growth factors. Dishes coated with a low ECM density (1 ng/cm2) supported hepatocyte attachment, but did not promote cell spreading or growth. Computerized image analysis confirmed that over 80% of cells remained free of contact with other cells under these conditions. Yet, these round cells maintained high levels of albumin gene expression as well as elevated secretion rates for multiple liver-specific proteins (albumin, transferrin, and fibrinogen), regardless of the type of ECM molecule used for cell attachment. When ECM coating densities were raised from 1 to 1,000 ng/cm2, cell spreading, expression of histone mRNA, DNA synthesis, and cell proliferation all increased in parallel. Activation of growth by high ECM densities was also accompanied by a concomitant down-regulation of differentiated functions and again, dishes coated with all four types of ECM molecules produced similar effects. Thus, the ability to switch hepatocytes from differentiation to growth (i.e., between different genetic programs) is not limited to a single ECM molecule, a distinct three dimensional ECM geometry, or due to alteration of cell-cell interactions. Rather, the regulatory signals conveyed by immobilized ECM molecules depend on the density at which they are presented and thus, on their ability to either prohibit or support cell spreading.
481 citations
TL;DR: This derivatization method produced chemically stable substrates which may be useful in studying receptor-mediated cell adhesion, as the quantity of peptide available at the surface may be precisely measured and controlled.
424 citations
TL;DR: Experiments using chondrocytes in a biodegradable polymer solution for the treatment of vesicoureteral reflux in an animal model found this system is able to correct reflux without any evidence of obstruction.
343 citations
TL;DR: Biomaterials play a critical role in the engineering of new functional genitourinary tissues for the replacement of lost or malfunctioning tissues and may provide bioactive signals required for the retention of tissue-specific gene expression.
Abstract: Biomaterials play a critical role in the engineering of new functional genitourinary tissues for the replacement of lost or malfunctioning tissues. They provide a temporary scaffolding to guide new tissue growth and organization and may provide bioactive signals (e.g., cell-adhesion peptides and growth factors) required for the retention of tissue-specific gene expression. A variety of biomaterials, which can be classified into three types – naturally derived materials (e.g., collagen and alginate), acellular tissue matrices (e.g., bladder submucosa and small-intestinal submucosa), and synthetic polymers [e.g., polyglycolic acid, polylactic acid, and poly(lactic-co-glycolic acid)] – have proved to be useful in the reconstruction of a number of genitourinary tissues in animal models. Some of these materials are currently being used clinically for genitourinary applications. Ultimately, the development or selection of appropriate biomaterials may allow the engineering of multiple types of functional genitourinary tissues.
337 citations
TL;DR: It is shown that, similar to natural macromolecules of the extracellular matrix, the synthetic polymers are able to participate in the control of cell function.
275 citations