Mammalian cell culture protein post-translational modification

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. 

Mammalian cells Get export of proteins Get desired post-translational modifications and products not likely to be immunogenic to humans Good expression systems available Large-scale growth of animal cells costly Great care needed to avoid contamination of cultures... 

Mammalian cell culture is more technically complex and more expensive than microbial cell fermentation. Therefore, it is usually only used in the manufacture of therapeutic proteins that show extensive and essential post-translational modifications. In practice, this usually refers to glycosylation, and the use of animal cell culture would be appropriate where the carbohydrate content and pattern are essential to the protein s biological activity, its stability or serum half-life. Therapeutic proteins falling into this category include EPO (Chapter 10), the gonadotrophins (Chapter 11), some cytokines (Chapters 8-10) and intact monoclonal antibodies (Chapter 13). 

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. 

This chapter describes some of the most important and well-studied forms of post-translational modifications of proteins, which have been associated with the production of glycoproteins as biopharmaceuticals from mammalian cell culture systems. Most attention is given to glycosylation because of its general importance for the activity of all these... 

Mammalian cell culture-derived proteins undergo post-translational modifications within the cell before they are secreted into the culture medium. A major posttranslational modification that can impact half-life, bioavailability, and even immunogenicity of therapeutic proteins is glyscoysla-tion." - Due to these potential effects, glycosylation is carefully monitored during cell line selection and process and formulation development. 

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... 

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