Mammalian cells, cultures

Fig. 3. Schematic of a fluidized-bed process for mammalian cell culture where D(02) = dissolved oxygen.

J. P. Mathei, ed.. Mammalian Cell Culture The Use of Serum-Free Hormone-SupplementedMedia, Plenum Press, New York, 1984. 

J. N. Thomas, in A. S. Lubrniecki, ed., Farge Scale Mammalian Cell Culture Technology, Marcel Dekker, New York, 1990, pp. 93—145. 

Mammalian Cells Unlike microbial cells, mammalian cells do not continue to reproduce forever. Cancerous cells have lost this natural timing that leads to death after a few dozen generations and continue to multiply indefinitely. Hybridoma cells from the fusion of two mammalian lymphoid cells, one cancerous and the other normal, are important for mammalian cell culture. They produce monoclonal antibodies for research, for affinity methods for biological separations, and for analyses used in the diagnosis and treatment of some diseases. However, the frequency of fusion is low. If the unfused cells are not killed, the myelomas 1 overgrow the hybrid cells. The myelomas can be isolated when there is a defect in their production of enzymes involved in nucleotide synthesis. Mammahan cells can produce the necessary enzymes and thus so can the fused cells. When the cells are placed in a medium in which the enzymes are necessaiy for survival, the myelomas will not survive. The unfused normal cells will die because of their limited life span. Thus, after a period of time, the hybridomas will be the only cells left ahve. 

Microcapsules can be used for mammalian cell culture and the controlled release of drugs, vaccines, antibiotics and hormones. To prevent the loss of encapsulated materials, the microcapsules should be coated with another polymer that forms a membrane at the bead surface. The most well-known system is the encapsulation of the alginate beads with poly-L-lysine. 

Pollack, R. (1981). Readings in Mammalian Cell Culture. Cold Spring Harbor Laboratories. Cold Spring Harbor, New York. 

Mammalian cells Cultured human lymphocytes Mitotic recombination Aberrant metaphases No data - L Vova 1984... 

Feuser, J., Halfar, M., Liitkemeyer, D., Ameskamp, N., Kula, M.-R., and Thommes, J., Interaction of mammalian cell culture broth with adsorbents in expanded bed adsorption of monoclonal antibodies, Process Biochem., 34,159,... 

Bertsche U. 1985. Micronucleus induction in mammalian cell cultures treated with ionizing radiations. Radiat Environ Biophys 24 27-44. 

Gorbsky GJ 1994 Cell cycle progression and chromosome segregation in mammalian cells cultured in the presence of the topoisomerase II inhibitors ICRF-187 [(+)-l,2-bis(3,5-dioxopiperazinyl-l-yl)propane ADR-529] and ICRF-159 (Razoxane). Cancer Res 54 1042-1048... 

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. 

Also, special vectors allowing expression in both insect cells and mammalian cell cultures from the same vector (pMamaBac [11] andpBacMam [12]) were described, though the amount required for mammalian transfection with one of these vectors is twofold higher than for insect cells, which makes it applicable only for assessment of suitability for a certain cell culture. 

In spite of several drawbacks (i.e. expensive and laborious handling procedures, low space-time yields (Table 2.1), high demand on biosafety, potential contaminations, limited applicability for continuous fermentations [129], and problems obtaining the same glycosyla-tion profile from batch to batch [130]), mammalian cell cultures are widely used for small-scale expression and more recently even on a multi-cubic-meter scale. The system works like insect... 

The combination of three-phase fluidization and cell culture may represent an ideal union of new technology and immediate application because the high-value products of mammalian cell culture require relatively small production scales (on the order of 100 liters rather than 100,000 liters), it is possible to investigate the usefulness of three-phase fluidization in what would otherwise be considered a pilot scale set up without having to build an expensive, large scale unit. 

Matthew JE, Nazario YL, Roberts SC et al (2002) Effect of mammalian cell culture medium on the gelation properties of Pluronic F127. Biomaterials 23 4615-4619... 

Applications of Spider Silk-ELP Fusion Proteins in Mammalian Cell Culture... 

In addition to the urgent problem of capacity, manufacturers have to cope with the operating costs of production, which are increased by the need for skilled personnel and expensive media components. Another cost driver is the inherent contamination risk when using mammalian cell culture systems. All materials must be checked closely for bacterial and viral contamination, and the presence of prions and endotoxins. This affects not only the manufacturing process, but also downstream materials and even human semm albumin (HSA) used for formulations. In the end, production costs add up to 100-1000 per gram of therapeutic protein. 

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... 

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