Monoclonal antibodies small-scale production

Laboratory based methods for small scale production of monoclonal antibodies... 

The main disadvantage of all these systems is the Hmitation of scale-up. Monoclonal antibodies are produced by multiplying the hollow fiber systems and stirred tank reactors with membrane aeration are known up to 100 liter. Small quantities of product can be produced by these systems but they are not suitable for real industrial scale-up. 

In this chapter the subject of scale-up is reviewed, which is taking small laboratory cultures (e.g. 10 ml) to industrial-scale processes (e.g. 10 000 litre), i.e. a 1 000 000-fold scale-up The aim of such scale-up is to provide more cells, and more cell product, in as efficient and cost-effective a manner as possible. Cell cultures have been used since 1954 for the production of human (e.g. polio, measles, mumps, rabies, rubella) and then veterinary (e.g. FMDV) vaccines (Griffiths, 1990a). Interferon was the next most important product to be developed, followed by monoclonal antibodies and a range of recombinant proteins. 

The most important technique for perfusion culture methods is to separate the concentrated cells and conditioned medium from the suspended culture broth. As noted above, the separation methods chiefly used are filtration with tubular and flat membranes as well as ceramic macroporous filters. These membrane reactors can be employed for both anchorage-dependent and suspension growing cells. Static maintenance type systems are commercially available for disposable reactors, and small size unit reactors from 80 ml to 1 liter are used for continuous production of monoclonal antibodies with hybridoma cells. The maintainable cell densities are about 10 -10 cells/ ml which is essentially mouse ascites level. However, in these systems, the cell numbers cannot be counted directly because the cells adhere to membranes or hollow fibers. Therefore, the measurement of cell density must use indirect methods. Such indirect methods include the assaying of the quantities of glucose consumption and the accumulation of lactate. The parameters of scale-up have not yet been established for these static methods. 

Advances in the development of modem chromatography materials and modem equipment have turned scale-up into a less critical issue than it was in the past. Usually, nonchromatographic parameters such as consistency of starting material or limited stability create problems. The scale-up of purification is usually aligned with the scale-up of fermentation. Different reactor types are often used for small and large scale, which may lead to a different composition of the impurities, product concentration, and even molecular structure. Maiorella et al. [90] demonstrated that bioreactor types and culture conditions influence the isoelectric pattern of a monoclonal antibody. This has a big impact on purification because different isoelectric patterns may lead to different solubilities and binding behavior to ion exchangers or other sorbents affected by ionic interactions. 

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