Animal cells, transformation

Occasionally, some of the animal cells in short-term cultures do not die, but instead survive indefinitely. These types of animal cell cultures, which can divide indefinitely, are called established cell lines. Established animal cell lines have been obtained from both normal and tumorigenic cells. Immortalized animal cell lines have also been successfully obtained from short-term cultures following their transformation with appropriate oncogenes. 

The serum requirement of many transformed animal cells is also reduced. The reduction in the serum requirement can, in many cases, be explained by a loss of some of the cells hormone, growth factor or adhesion requirements. The altered hormone, growth factor, or attachment requirements can be studied by growing the cells in serum-free medium. 

Special reactors are required to conduct biochemical reactions for the transformation and production of chemical and biological substances involving the use of biocatalysts (enzymes, immobilised enzymes, microorganisms, plant and animal cells). These bioreactors have to be designed so that the enzymes or living organisms can be used under defined, optimal conditions. The bioreactors which are mainly used on laboratory scale and industrially are roller bottles, shake flasks, stirred tanks and bubble columns (see Table 1). 

Different animal cell types display different properties pertinent to their successful culture. Those used to manufacture biopharmaceuticals are invariably continuous (transformed) cell lines. Such cells will grow relatively vigorously and easily in submerged culture systems, be they roller bottle or bioreactor based. 

Evaluation of signs of cell transformation/growth factor dependence-effect on animal cells, normal human cells and cells prone to transform easily. 

One of the major disadvantages of utilizing enzymes or semisynthetic enzymes for chemical transformations is the fact that large quantities of pure enzyme are needed for preparative scale. This disadvantage is contrasted with whole cell systems (bacteria, fungi, plant/animal cells) because they are easily available in large quantities through... 

In vitro in animal cells, DNA repair and hprt gene mutations were induced by 1,2-di-chloroethane. Cell transformation was observed in Syrian hamster embryo cells in a single study but not in two independent studies with BALB/c-3T3 cells. 1,2-Dichloro-ethane induced gene mutations in human lymphoblastoid cell lines. 

Epoxybutane induced morphological transformation, sister chromatid exchanges, chromosomal aberrations and mutation in cultured animal cells however, in a single study, it did not induce unscheduled DNA synthesis in rat primary hepatocytes. It induced sex-linked recessive lethal mutations and translocations in Drosophila melanogaster, mitotic recombination in yeast, and mutations in yeast and fungi. 1,2-Epoxybutane induced DNA damage and mutations in bacteria. 

Ethylene dibromide induced gene mutations, sister chromatid exchanges, chromosomal aberrations and cell transformation in animal cells. It induced mutations in two human lymphoblastoid cell lines, AHH-1 and TK6 in the absence of exogenous metabolic activation. Administration of radiolabelled ethylene dibromide to Wistar rats and BALB/c mice resulted in binding to DNA, RNA and proteins. [The nature of the binding was not characterized.]... 

Phenyl glycidyl ether induced mutations in bacteria and transformation in mammalian cells in vitro (in a Syrian hamster embryo cell clonal assay and in an assay for the enhancement of viral transformation), but did not induce chromosomal aberrations in animal cells in vitro or either micronuclei or chromosomal aberrations in vivo. It did not induce dominant lethal effects in rats (IARC, 1989). 

The transformation of animal cells by foreign genetic material offers an important mechanism for expanding our knowledge of the structure and function of animal genomes, as well as for the generation of animals with... 

Available methods for carrying DNA into an animal cell vary in efficiency and convenience. Some success has been achieved with spontaneous uptake of DNA or electroporation, techniques roughly comparable to the common methods used to transform bacteria. They are inefficient in animal cells, however, transforming only 1 in 100 to 10,000 cells. Microiqjection—the injection of DNA directly into a nucleus, using a very fine needle—has a high success rate for skilled practitioners, but the total number of cells that can be treated is small, because each must be injected individually. 

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