Cell Contact inhibition

Many vimses, both DNA and RNA containing, will cause cancer in animals. This so-called oncogenic achvity of a vims can be demonstrated by the observahon of tumour formahon in inoculated experimental animals and by the ability of the vims to transform normal tissue culture cells into cells with malignant characteristics. These transformed cells are easily recognizable as they exhibit such properties as rapid growth and frequent mitosis, or loss of normal cell contact inhibition, so that they pile up on top of each other instead of remaining in a well-organized layer. 

As was stressed by Professor Ubbelohde, in the process of cell recognition not only the lateral diffusion of the binding sites has to be considered, but also the mechanical effects resulting from the local change of surface tension, inducing convection at the cell surface. It is well known, in the cell-to-cell contact inhibition of motion, in tissue culture, that a cell approaches another cell by touching it by means of microvilli and that this process can be affected when adding surfactants to the culture. Now the point is, What is the relative importance of both diffusion and convection Well, in binary surface films, it was observed that the transport process induced by two-dimensional convection is much more rapid than the two-dimensional diffusion. 

Tissue injury impairment of cell contact inhibition... 

Experimental infection of animals has shown that certain viruses can induce cancer. This oncogenic activity can also be demonstrated in vitro in cell cultures. Cells surviving viral infection can change dramatically, acquiring the characteristics of tumour cells. These transformed cells exhibit frequent mitosis. They also lose the property of cell contact inhibition, so they tend to pile up on top of each other rather than remaining as organized monolayers. 

We are now preparing and studying membrane models formed by ternary systems amphipatic block copolymer/lipids/water. From the interaction with our polymeric models of lectins (lectins are proteins or glycoproteins specific of different sugar residues] we hope to obtain informations about the respective parts played by the different carbohydrate chains and the polypeptide skeleton of glycoproteins and perhaps help to throw some light on problems as important as cell recognition and cell contact inhibition. 

Kidney cells grown in culture with liver cells seek out and make contact with other kidney cells and avoid contact with liver cells. Cells grown in culture grow freely until they make contact with one another, at which point growth stops, a phenomenon well known as contact inhibition. One important characteristic of cancerous cells is the loss of contact inhibition. 

Contact inhibition is observed in the process of wound healing and describes the ability of a tissue to stop cell proliferation again after cellular multiplication has filled up the defect caused by a wound. 

Nagasaki, T., Chapin, C.J., Gundersen, G.G. (1992). Distribution of detyrosinated microtubules in motile NRK fibroblasts is rapidly altered upon cell-cell contact Implications for contact inhibition of locomotion. Cell Mot. Cytoskel. 23,45-60. 

ORDINARY DIFFERENTIAL EQUATION MODELS 17.3.1 Contact Inhibition in Microcarrier Cultures of MRC-5 Cells... 

Contact inhibition is a characteristic of the growth of anchorage dependent cells grown on microcarriers as a monolayer. Hawboldt et al. (1994) reported data on MRC5 cells grown on Cytodex II microcarriers and they are reproduced here in Table 17.13. 

Vero Cells Grown on Microcarriers (Contact Inhibition)... 

Zygourakis, K. Bizios, R. and P. Markenscoff, "Proliferation of Anchorage Dependent Contact Inhibited Cells Development of Theoretical Models Based on Cellular Automata", Biotechnol. Bioeng., 36, 459-470 (1991). 

The scoring of foci was carried out according to the recommended guidelines. Only foci considered as positive (type III), showing deeply basophilic, dense multilayering of cells, random cell orientation at all parts of the focus edge, invasion into the surrounding contact-inhibited monolayer, and domination of spindle-shaped cells, were counted. 

Szczepanik M, Bryniarski K, Tutaj M, Ptak M, Skrzeczynska J, Askenase PW, Ptak W Epicutaneous immunization induces T-cell receptor CD4 CDS double-positive non-specific suppressor T cells that inhibit contact sensitivity via transforming growth factor-p. Immunology 2005 115 42-54. 

The body s cells are normally subject to strict social control. They only divide until they come into contact with neighboring cells cell division then ceases due to contact inhibition. Exceptions to this rule include embryonic cells, cells of the intestinal epithelium (where the cells are constantly being replaced), cells in the bone marrow (where formation of blood cells takes place), and tumor cells. Uncontrolled cell proliferation is an important indicator of the presence of a tumor. While normal cells in cell culture only divide 20-60 times, tumor cells are potentially immortal and are not subject to contact inhibition. 

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