Cell attachment properties

Extension of the culture time up to, respectively, three days for the P (MMA MA APC) copolymer and four days for the PCPUR copolymers, showed no evolution in the cell attachment properties on the PC containing surfaces, as opposed to the PC-free surfaces (Si02 reference as well as P(MMA MA) polymer). Indeed, after 72 h in SCM, a large population of cells were attaching and differentiating on P(MMA MA) as can be seen from Fig. 16a. In contrast, on the... 

Historically, these peptides were identified by isolating domains ofinterest from naturally evolved proteins. The tripeptide RGD sequence (arginine-glycine—aspartic acid), a commonly used cell-adhesion domain, is a prime example of this. RGD was isolated in 1983 from the extracellular and plasma protein fibronectin and was identified as the minimal sequence necessary to promote cell-attachment properties (Pierschbacher and Ruoslahti 1984). Other commonly used domains include elastin-hke sequences, which are derived from the protein elastin found in connective tissue (Meyer and Chilkoti 2002), and recombinant-silks (Prince et al. 1995). Both of these peptide domains are used to confer their unique mechanical properties (i.e., resilience, elasticity, and strength) to the resulting biomaterial. 

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. 

A variety of substrate- and cell-attached factors influence neural development by regulating adhesion properties of cells (see Ch. 7). Interactions occur directly between cells or between a cell and the extracellular matrix (see Ch. 2). The molecules mediating these interactions have been implicated in regulating the specificity and timing of cell-cell adhesion and the consequences on cell morphology and physiology. Hence, they influence the ability of cells not only to migrate but to sort themselves out and to stabilize spatial relationships considered important for the process of differentiation. 

Cheresh DA, Spiro RC. Biosynthetic and functional properties of an Arg-Gly-Asp directed receptor involved in human melanoma cell attachment to vitronectin, fibrinogen, and von Willebrand factor. J Biol Chem 1987 262(36) 17,703-17,71 I. 

Fig. 6.3. Micelles, liposomes and cell membranes. Micelles are collections of lipid molecules that are relatively nonpolar internally and polar externally. This arrangement allows relative water-solubility of the micelle as a whole. Liposomes contain lipid molecules in a bilayer. They may be used as artificial vehicles for trapping and delivery of drugs to specific tissues. They are also useful as models of cell surfiice function. A real cell membrane is not only a lipid bilaycr, but also includes proteins, glycoproteins, glycolipids, and lipoprotein molecules. The glyco attachments on the outer surface may be important in labeling cells with specific cell-surfece properties.

The membrane material is important for cell attachment and growth. Common materials are polycarbonate, cellulose esters (acetate and nitrate) and PET (polyester). These materials sometimes need to be coated for cells to grow and differentiate. The different membrane materials have very different optical and mechanical properties, which must be considered when planning any experiment. 

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