Animal Cell Cultivations

Hua J, Erickson LE, Yiin T-Y, Glasgow LA. A review of the effects of shear and interfacial phenomena on cell viability. Grit Rev Biotechnol 1993 13(4) 305-328. Tramper J, de Gooijer KD, Vlak JM. Scale-up considerations and bioreactor development for animal cell cultivation. Bioprocess Technol 1993 17 139-177. Griffiths B, Looby D. Scale-up of suspension and anchorage-dependent animal cells. Methods Mol Biol 1997 75 59-75. 

Batch cultivation is perhaps the simplest way to operate a fermentor or bioreactor. It is easy to scale up, easy to operate, quick to turn around, and reliable for scale-up. Batch sizes of 15,000 L have been reported for animal cell cultivation [2], and vessels of over 100,000 L for fermentation are also available. Continuous processes can be classified into cell retention and non-cell retention. The devices typically used for cell retention are spin filters, hollow fibers, and decanters. Large-scale operation of continuous processes can reach up to 2,000 L of bioreactor volume. Typically, the process is operated at 1-2 bioreactor volumes... 

J. Tramper, K. D. de Gooijer. J. M. Vlak. Scale-up considerations and bioreactor development for animal cell cultivation. Bioprocess Technol 17 139-177, 1993. 

The different operation modes used in microbial fermentations are employed also in animal cell cultivation. Although many different classifications can be adopted, the most general is the one that considers the following operation modes batch, fed-batch, continuous, and perfusion, which is a continuous mode with cell recycle/retention (Castilho and Medronho, 2002). 

Although simple, the use of bubble aeration in animal cell cultivation requires the solution of certain technological challenges for its implementation, since one of the most characteristic features of animal cells is their low resistance to mechanical stresses. Cell membranes have a mechanical resistance that is much lower than that of microbial cell walls. According to Castilho and Anspach (2003), shear stresses in the order of 60 Pa are critical for cell death. 

When stirred-tank bioreactors started to be used for animal cell cultivation, many problems related to deleterious effects of agitation on cell viability were observed. Flowever, it was noted that the use of large impellers rotating at low speeds could minimize mechanical damage to the cells. The most widely used impeller types are marine (Chisti, 1993)... 

The scientific and technological achievements of the last decades have allowed the discovery and production of new biological medicines, or substitution of those previously extracted from animal sources, like insulin and growth hormone. Most of those medicines are proteins obtained by animal cell cultivation, which differs from bacteria and yeast in that animal cells carry out post-translational modifications needed for biological activity and similar to the natural protein. Biopharmaceutical production in mammalian cells, including hormones, monoclonal antibodies (mAbs), vaccines, and other molecules with medical interest, involves high cost processes due to factors such as ... 

Inner surface of an industrial-scale stirred-tank bioreactor for animal cell cultivation. Photo taken by Dr. Ernesto Chico, Center of molecular Immunology, Cuba. 

Internal surface of a 1000 L bioreactor for animal cell cultivation. It is also possible to observe the three-blade impeller and the baffles, which are flat vertical parts attached to the internal bioreactor surface with the aim of avoiding vortex formation. 

N., and Schasfoort, R. (1984) Large scale animal cell cultivation for production of cellular biologicals. Dev. Biol. Stand. 60 229-236. 

Oeggerli, A., Eyer, K., and Heinzle, E. (1995) On-line gas analysis in animal cell cultivation I. Control of dissolved oxygen and pH. Biotechnol. Bioeng.. 45 42-53... 

In this study two different flow-injection immunoassays are presented as well as the flexible automation system CAFCA (Computer Assisted Flow Control Analysis), which has been used for their control, uptake measurement, evaluation and visualization. Both immunoassays (a heterogeneous and a homogeneous assay) are based on the principles of flow-injection analysis and were developed for reliable, fast monitoring of relevant proteins in animal cell cultivation processes. Off-line applications of measurements of medium samples as well as online application during a mammalian cell cultivation are presented. All results are compared to results obtained with ELISA (Enzyme Linked Immunosorbend Assay). The requirements of the automation of flow-injection immunoassays with respect to their flexible control are discussed. 

Passive antibody vaccines have been prepared up to now from human blood serum. Consequently, there has been no need for cultivation methods beyond vaccination and conventional harvest of antibody-containing blood from donors. Due to safety concerns over using human blood, passive vaccines will likely be monoclonal antibodies or cocktails thereof prepared in vitro by the cultivation of hybridoma or myeloma cell lines. This approach is under investigation for anti-HIV-1 antibodies [Emini et al., 1992]. Cultivation of these cell lines involves the same principles of animal cell cultivation as described above, with the exception that hybridomas can be less fastidious in nutritional requirements, and they do not require surface attachment for growth. These features will allow for defined serum-free media and simpler cultivation vessels and procedures. 

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