Adhesion of cells

Bell, 1978] Bell, G. I. Models for the specific adhesion of cells to cells. Science. 200 (1978) 618-627... 

Mechanisms of Leukocyte Adsorption. The exact mechanism of leukocyte adhesion to filter media is not yet fuUy understood. Multiple mechanisms simultaneously contribute to the adhesion of cells to biomaterials, however, physical and biological mechanisms have been distinguished. Physical mechanisms include barrier phenomenon, surface tension, and electrostatic charge biological mechanisms include cell activation and cell to cell binding. 

The binding of integrins to certain ligands is mediated by a short amino acid sequence. Thus, the binding site for fibronectin is confined to a sequence of four amino acid residues, Arg-Gly-Asp-Ser (RGDS) (R7). Synthetic peptides containing the RGDS sequence prevented adhesion of cells to fibronectin (B4, R7) and also inhibited metastasis formation in animal models (B4, R7). 

Curtis ASG (1964) The mechanism of adhesion of cells to glass a study by interference reflection microscopy. J Cell Biol 20 199-215... 

The free energy change for adhesion of cells from a liquid suspension onto a solid substrate is given by... 

In these two examples, we described polyurethane as a physical device possessing such important features as a high surface-to-volume ratio and a high void volume. We also talked about it as a chemical system for solid solvent extraction and as a polymer system for enhancing tlie adhesion of cells. We will go into much more detail, but we have begun the process of considering polyurethane for uses beyond furniture cushions. 

Improve adhesion of cells and micro-organisms to obtain bio-functional surfaces... 

Some authors claim that liposaccharides can depress the content of TNF-a and increase the activity of superoxide dismutase (SOD) and catalase, thus—via mediators—they can affect the immune system (Can et al. 2003). It has been demonstrated that the NF-p transcription factor, (highly sensitive to the redox potential in its environment), which regulates synthesis of many mediators—cytokines, associated with inflammatory condition and the phenomenon of adhesion of cells— becomes deregulated in old age. Defense functions in such cases (and primarily in arthritis and arthritis-related conditions) are said to be performed by antioxidants (including a-lipoic acid), which can modulate the activity of monocytes and inhibit changes caused by deregulating of the transcription factor NF-kB under the influence of redox conditions in elderly people (Lee and Hughes 2002). 

Fibronectin is found, in related forms, in serum as well as on the surface of normal, but not transformed cells. Addition of fibronectin to transformed cells causes a partial return to the normal phenotype in that it increases the adhesion of cells to other cells and to the substratum. It will also increase the saturation density achieved by 3T3 cells (Yamada et al., 1982). In contrast, antibodies to fibronectin will induce some of the characteristics of transformed cells in otherwise normal cells. 

Deposition and adhesion of cells on surfaces play an important part in many biological processes. For example, blood cell deposition and adhesion on surfaces are essential in the vital process of haemostasis and fundamental in the events leading to thrombus formation. Also, malignant cell adhesion on various tissues is responsible for the growth of secondary tumors, after being carried in the blood stream from the primary tumor location. 

Introduction. Cell deposition on various surfaces plays an important part in the initiation of many biological processes, such as hemostasis, thrombosis and growth of secondary tumors. It consists of two main stages (a) the conveyance of cells to the vicinity of the interacting surface, and (b) the adhesion of cells to this surface. In most of the biological systems, the main field which conveys the cells to the surface is a flow field. However, for experimental studies of the process of adhesion per se, it is convenient to use a stagnant solution in which cells are conveyed to the surface by gravity (Weiss and Harlos, 1972) or by a... 

Weiss, L. and J. P. Harlos. 1972. Some Speculations on the Rate of Adhesion of Cells to Coverslips, J. Theor. Biol. 37, 169-179. 

Adhesion of Cells of Various Ages to a Polystyrene Surface... 

Proteoglycans resemble polysaccharides more than proteins in as much as the carbohydrate makes up as much as 95% of the hiomolecule hy weight. Proteoglycans function as lubricants and structural components in connective tissue, mediate adhesion of cells to the extracellular matrix, and bind factors that stimulate cell proliferation. 

Hemostasis and inflammation involves adhesion of cells in the flowing blood to the vessel wall. Three main families of receptors are involved. 

The adhesion of cells to each other is normally due to interactions that involve a number of proteins of the extracellular matrix and the plasma membrane. Cadherin is a membrane-boimd protein. The N terminus of cadherin is extracellular. The N termini of cadherins sticking out of adjacent cells bind to each other. This interaction requires calcivun ions, hence the name Cadherin. An intracellular interaction is also required for adhesion to occur between cells. The C terminus of cadherin contacts the cytosol and binds to a protein called catenin (pronounced ca-TEE-nin). Catenin, in turn, binds to the cytoskeleton. The cytoskeleton is a network of proteins that crisscross about the plasma membrane and through the cell. Defects in the cadherin gene have been found in many samples of colorectal cancer. These mutations tend to occur in the N-terminal region, i.e., in the extracellular calcium-binding domain. 

Negatively charged acylneuraminic acid residues impart a certain strength to cell membranes because of their mutual repulsion, and influence the mutual adhesion of cells in the organ structure. Whereas neuraminic acid allows the aggregation of embryonal muscle cells of the hen, presumably via Ca bridges, it prevents spontaneous clumping of blood platelets, and it so opposes any undesirable formation of blood clots. 

Both reversible and irreversible attachments are possible. Microbial cells can be held in close proximity to a surface by the long-range forces, but still be capable of Brownian motion. Under the fiow conditions, mild shear forces, brought about by fiow and disturbances in the viscous sublayer, may also be present. These effects may restrict or prevent attachment. It is anticipated that this could be the situation if no conditioning molecules were residing on the surface and would explain the reason for the observed delay in biofilm formation under fiowing conditions. Any adhesion of cells under these conditions could be said to be reversible. 

Inside the human body, cell adhesion to foreign biomaterial surfaces is mediated by a layer of proteins found in the blood or serum. Biomaterials that are able to control the adsorption of blood proteins will be able to control selectively the adhesion of cells. This function underlies the so-called biocompatibility of... 

---