Extracellular matrix composition

Abrass CK, Berfield AK, Stehman-Breen C, Alpers CE, Davis CE. Unique changes in interstitial extracellular matrix composition are associated with rejection and cyclosporine toxicity in human renal allograft biopsies. Am J Kidney Dis 1999 33 11 -20. 

Morrison JC, Jerdan JA, L Hernault NL, Ouigley HA. The extracellular matrix composition of the monkey optic nerve head. Invest Ophthalmol Vis... 

Zgheib J, Xu J, Liechty KW. Targeting inflammatory cytokines and extracellular matrix composition to promote wound regeneration. Adv Wound Care (New Rochelle) 2014 3 344-55. 

Additional cell culture experiments were carried out on patterned 3D substrates in order to combine the spatial constraints of a stem cell niche with the influence of different extracellular matrix components of its microenvironment. Therefore, sihcone molds of cavities with a size of 10 to 80 p,m and a depth of 10 pim were coated with reactive maleic anhydride copolymers and subsequently reconstituted assembUes of collagen fibrils and cofibrils were immobilized on top of it. Hematopoietic stem cells were seeded onto these functionalized cell carriers. Depending on the size of the cavities cells differentially adhered to these structmes as exemplarily shown in the inset of Fig. 10. In initial experiments adhesion and proliferation was followed over a time period of 3 days. As shown in Fig. 10 the cells tend to preferentially adhere to an intermediate size of cavities. This result points to a balanced equilibrium of cell-ceU contacts and cell-matrix contacts for the homing and proUferation of hematopoietic stem cells, which is in agreement with the observed small hematopoietic stem cell clnsters foimd in vivo [113]. Fm-ther experiments will foUow np on these observations in order to imravel the influence of different extracellular matrix compositions combined with microcavities. 

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

The vitreous is a transparent extracellular matrix occupying the space between the posterior lens and the retina and, in the majority of vertebrate species, constitutes the major f)art of the volume of the eye. Embryo-logically it can be considered as the basement membrane of the retina. It provides a mechanical support for surrounding tissues and acts as a shock absorber by virtue of its viscoelastic properties (Balzas and Delinger, 1984). Vitreous consists mainly of water (98%) and colloids (0.1%) with ions and low molecular weight solutes making up the remainder. It is not fully developed at birth, and changes in both volume and chemical composition occur postnatally. 

The sole purpose of the filter support and any applied extracellular matrix is simply to provide a surface for cell attachment and thus to provide mechanical support to the monolayer. However, the filter and matrix also can act as serial barriers to solute movement after diffusion through the cell monolayer. The important variables are the chemical composition of the filter, porosity, pore size, and overall thickness. In some cases, pore tortuosity also can be important. It is desired that the filter, with or without an added matrix, provide a favorable surface to which the cells can attach. However, in some cases these properties can also result in an attractive surface for nonspecific adsorption of the transported solute. In these instances, the appearance of the solute in the receiver compartment of the diffusion cell will not be a true reflection of its movement across the mono-layer. Such problems must be examined on a case-by-case basis. 

Bone is an extremely dense connective tissue that, in various shapes, constitutes the skeleton. Although it is one of the hardest structures in the body, bone maintains a degree of elasticity owing to its structure and composition. It possesses a hierarchical structure and, as most of the tissues, is nanostructured in fact, it is a nanoscaled composite of collagen (organic extracellular matrix) and hydroxycarbonate apatite, (HCA, bone mineral). This nanostructure is in intimate contact with the bone cells (several microns in size), which result (at the macroscopic level) in the bone tissue. Figure 12.2 shows the bone hierarchical ordering from the bone to the crystalline structure of HCA. 

Vardi A, Formiggini F, Casotti R, De Martino A, Ribalet F, Miralto A, Bowler C (2006) A stress surveillance system based on calcium and nitric oxide in marine diatoms. PLoS Biol 4 411 119 Vorwerk S, Somerville S, Somerville C (2004) The role of plant cell wall polysaccharide composition in disease resistance. Trends Plant Sci 9 203-209 Vreeland V, Laetsch WM (1990) A gelling carbohydrate in algal cell wall formation. In Adair WS, Mecham RP (eds) Organization and assembly of plant and animal extracellular matrix. Academic, San Diego, CA, ppl 37—171... 

As outhned earUer every single step of hematopoiesis is regulated and controlled in vivo by the cell s microenvironment. This not only includes the composition and concentration of growth factors, but also the local oxygen concentration, the pH, the osmolaHty, the supply of nutrients and the cellular and molecular surrounding of the cells (cell-cell contact, adhesion molecules and extracellular matrix). All these parameters affect the fate of the cell and, to estabUsh a cell culture process to cultivate or generate a specific subpopulation, the influence of all these factors has to be considered in the experimental set-up. In the following sections these parameters will be discussed in brief. 

Our understanding of the mechanisms of biomineralization is superficial435. In the past 20 years, most researchers have concentrated upon the extracellular concepts of epitaxy, matrix composition and solubility products while recently the role of cellular organelles and enzymes have attracted more attention. But there are some accepted principles which necessarily carry theoretical implications445. ... 

The central event in the development of liver fibrosis is the enhanced sinusoidal deposition of extracellular matrix proteins that are mainly produced by activated HSC [86, 112, 113] and to a minor extent by endothelial cells [44-46] and hepatocytes [114, 115]. So far, no evidence has been found that KC are directly involved in the production of extracellular matrix proteins [39]. The accumulation of extracellular matrix proteins is caused by a disturbed balance between the synthesis and the degradation of the matrix proteins. This imbalance leads to a 5 to 10-fold increase in the total amount of matrix molecules and to an altered composition of the extracellular matrix. In contrast to normal livers, the sinusoids in fibrotic livers are stuffed with the fibrillar collagens type I and III. This colla-genization of the sinusoids, referred to as sinusoidal capillarization, causes severe disturbances of the blood flow and an impaired exchange of proteins between the liver cells and blood. Furthermore, this capillarization is accompanied by a loss of fenestration of the sinusoidal endothelial lining, which further hampers the diffusion of proteins between plasma and hepatic cells. 

Katz BZ, Zamir E, Bershadsky A et al (2000) Physical state of the extracellular matrix regulates the structure and molecular composition of cell-matrix adhesions. Mol Biol Cell 11(3) 1047-1060... 

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