Mammalian cell culture advantages

Insect cell systems represent multiple advantages compared with mammalian cell cultures (1) they are easier to handle (Table 2.1) (2) cultivation media are usually cheaper (3) they need only minimum safety precautions, as baculovirus is harmless for humans (4) they provide most higher eukaryotic posttranslational modifications and heterologous eukaryotic proteins are usually obtained in their native conformation (5) the baculovirus system is easily scalable to the bioreactor scale. However, because of the viral nature of the system, continuous fermentation for transient expression is not possible - the cells finally die. 

The third time constraint depends on whether the product can be extracted from seeds or fruits. This uncouples protein expression and purification. Large batches of seeds containing the recombinant protein can be produced and stored at low costs. Provided the protein remains stable in the stored seeds, purification can be carried out on demand or shifted according to free capacities. The advantage of one large harvest, with seeds mixed to uniformity, is that this allows production on demand. In contrast, mammalian cell culture is prone to minor batch-to-batch variations in... 

One system uses mouse lymphoma cells and detects mutations that cause deficiency of thymidine kinase (TK). Another uses Chinese hamster cells and detects mutations in the gene that produces hypoxanthine-guanine phosphoribosyl transferase (HGPRT). Both tests cure efficient, are widely applied, and can be completed in a few weeks. Although not as simple, rapid, and efficient as the Salmonella tests, they have the advantage of being done in a eukaryote. Mammalian-cell cultures cure also used to test for chromosomal mutation. 

Mammalian cell culture is a technology used for the production of recombinant proteins of therapeutic use, as they can secrete proteins with post-translational modifications similar to those present in human proteins. The most important advantages of this capacity of the mammalian cell lines are that they secrete a protein with the similar characteristics to the original protein, so that the protein can be used for human treatment without generating immunological responses. 

Despite these disadvantages, the major benefit of transgenic technology offers a means to produce proteins at a very low cost. Mammalian cell culture systems are often used for expression of recombinant human proteins (rHP), as the latter can only be obtained in a biologically active conformation when produced in such cells. However, this approach has limited production capacity and is expensive. In contrast, the production of rHP in milk of transgenic cattle is a safe and less-expensive alternative with the advantage of better protein output (Brink et al., 2000). 

Fig. 3 SWOT analysis of plant expression systems. Plant expression systems have a lot of advantages (plus) over other systems and are therefore mostly shown on the right-hand side of the picture (Raskin I et al., Plants and human health in the twenty-first century. Trends In Biotechnol. 2002 20, 522-531.). Herein different systems (transgenic animals, mammalian cell culture, plants, yeast, and bacteria) are compared in terms of speed (how quickly they can be developed), operating and capital costs...

Mammalian cell cultures have been used as the basis of several systemsin detect ng the potential carcinogenic activity of chemicals. Basically, two general approaches have been utilized continuous cell lines and primary cell cultures. Cell lines have the advantage of ease of use, in that cultures do not have to be obtained fresh from animals prior to each test, but may be maintained for months to years by proper subculturing techniques. They have the disadvantage of possessing one or more "transformed" characteristics (e.g., immortality). In some cases cell lines may also lack certain enzyme systems required for metabolic activation of chemicals. Some of the cell lines used for transformation assays include the murine (BALB/3T3) A31 system ( ), and the baby kidney-21 (BHK-21) systems (43). 

Some years ago Rose was the first to draw attention to the possible cytotoxic and carcinogenic role of arylnitrenes. Recently, photolysis of 2-azidofluorene in situ has been used as a probe for chemical carcinogenesis in mammalian cell cultures. It has the advantage of bypassing metabolic activation. Clearly, one can expect to see an increase in the use of azides, which are structurally related to known carcinogens, as specific photoaffinity labels in chemical carcinogenesis studies. 

One major advantage of monoclonal antibodies from plants is the potential low cost of large-scale production. There are commercial companies (such as EPIcyte Pharmaceutical Inc) who are planning clinical dials for plant-produced secretory antibodies for human therapy. These so-called plantibodies can be produced at an estimated cost of 0.01 to 0.1/mg as opposed to 1 to 5/mg for production from cell culture processing of animal-derived hybridomas. The cost of microbial fermentation is lower than that of mammalian cell culture but bacteria lack the ability for efficient multimeric protein assembly and of any post-translational modification. A further potential advantage of the plantibodies is delivery by consumption of plant tissue and thus avoiding any need of purification. These possibilities are particularly applicable in certain cases such as the previously shown ability of a plant-produced... 

MammaBan. For mammalian proteins, mammalian cells offer the most natural host for expression. Problems of incorrect processing and post-translational modification are avoided using these cells. Mammalian cells are usually grown in continuous cell culture, reducing the variabiUty in results (see Cell CULTURE technology). Moderate-level production of native protein is possible. The procedure, however, is slow and very cosdy, and the level of protein expression is low. Thus large-scale production of proteins in mammalian cells is not practical. When low quantities of protein are sufficient, this system offers the several advantages described. 

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