Cell Adhesion Experiments

For a more comprehensive treatment of the concepts discussed here, the reader is referred to an excellent review by Wilson et al. [91]. In summary, one has to keep in mind that the composition of a protein film interacting with cells in vitro (and more so in vivo) generally differs from the initially deposited physisorbed proteins, especially if long-term experiments are conducted. Nevertheless, protein-based surface films have often been shown to provide an excellent platform for cell adhesion experiments in which the precise control of the cell-surface interactions does not play a key role. 

Fig. 11.5 Cell adhesion experiment. Confocal laser scanning microscopy of endothelial cells growing on (A) unmodified and (B) Min3-modified PTFE.

Graft-Polymerization of Product c and Cell Adhesion Experiment. A... 

PLGA/HAp composites were also produced by colloidal non-aqueous chemical precipitation at room temperature by Petricca and coworkers [158]. The shape of the scaffolds with homogeneous distribution of HAp particles in PLGA matrix was easily engineered, and the mechanical properties of the PLGA/HAp composites indicated that the materials are suitable as bone substitution scaffolds. The decreased tensile strength was attributed to the presence of micropores within the scaffold, which are created upon removal of the ammonium nitrate, a by-product of the synthesis. The novelty of the process is the ability to incorporate up to 30 wt% HAp within the polymer matrix, thereby maximizing the material osteoconductivity, as evidenced by osteoblast-like cell adhesion experiments. 

From the result of contact angle measurements, it was expected that there would be no significant difference between PAS and SILASTIC 500-1 in the BSA adsorption and the cell adhesion. In the BSA adsorption test, this expectation seemed to hold. In the cell adhesion experiment, however, the PASs, which showed almost the same protein adsorption behavior, exhibited different cell adhesiveness. The number of adherent cells on PAS-41 and 71 were drastically decreased. Conversely, the numbers of the adherent cells on... 

Recent experiments have suggested that the tip link, a complex of two or three braided glycoprotein filaments [19], may be made in part from cadherin-23, a Ca2+-dependent cell-adhesion molecule [20], Moreover, cadherin-23 can interact directly or indirectly with myosin- lc, suggesting that these two molecules form part of the transduction complex in hair cells [20]. 

In an effort to identify the number of integrins required to trigger the formation of a stable FA, Spatz and co-workers studied a REF cell line on smaller nanostructured micropatterns. These experiments revealed that a minimum of six integrins per adhesive micropatterns were necessary to observe persistent cell adhesion. Adhesive islands with a side length larger than 1 pm induce the formation of FAs rich in paxillin, an integrin adaptor protein associated to actin fibres. These... 

Sortino et al. reported the use of light irradiation on SAMs supporting the anticancer drug flutamide to study its photoreactivity and product release of nitric oxide. The authors were able to conduct studies in the absence of noxious side effects such as singlet-oxygen photosensitization and observed that nitric oxide production halted when the light was turned off [103], Another photoactive molecule, azobenzene, has recently been exploited in the SAM community to aid in studies on cell adhesion and enzyme inhibition [104], Pearson and coworkers described the use of photoisomerizable SAMs of azobenzene to conduct a series of serine and cysteine protease inhibition experiments. When light of 340-380 nm is used, the... 

It is interesting to note that when the adhesion of 3T3 cells to the surface was re-tested at 20 degrees centigrade (room temperature) there was zero adhesion at 15 mins and only 52% adhesion at 30 mins. Therefore, the human primary fibroblast adhesion experiment was repeated at both 37 and 20 degrees centigrade (Figure 4). 

Carbohydrate-carbohydrate interactions have been suggested as mediators of cell adhesion and aggregation. Studies of four different interactions— sponge cell aggregation, embryo and myelin compaction, and melanoma cell adhesion— have provided insights into the role of the saccharides in these events. The biological context of these associations as well as the results of experiments using biophysical and chemical model systems are described. 

Cellular glue. A trisaccharide unit of a cell-surface glycoprotein is postulated to play a critical role in mediating cell-cell adhesion in a particular tissue. Design a simple experiment to test this hypothesis. 

Experiments with solids immersed in cell culture media, with and without living cells present, convincingly demonstrate the absolute condition that protein-dominated films accumulate at the solid-liquid boundaries prior to cell adhesion. The reality and speed of this spontaneous, adsorptive event are documented by using infrared-transmitting, multiple internal reflection plates as the immersed solid with care to prevent film transfer from gas-liquid interfaces. 

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