Which culture method is best to generate reagents with native biological specificity?
Cell culture methods vary a lot with respect to their ability to generate secreted proteins and antibodies that possess true biological specificity. Culture methodology is therefore a critical consideration for a manufacturer of serological test kits where excellent specificity is a priority. To this end a key goal would be to meet minimum physiological criteria for uniform and consistent protein glycosylation via the optimisation of culture conditions. A practical, easy-to-implement approach that can mimic in vivo-like cell culture conditions is therefore highly desirable.
Imagine a large mass of cells in continuous 3D culture, capillarized and continuously nourished and oxygenated in such a way as to resemble living tissue. Imagine regularly harvesting the proteins secreted by this cultured mass of cells: now you have just visualised how hollow fibre cell culture works. By maintaining constant conditions, without shear forces on the cells, with a continuous supply of oxygen and nutrients and elimination of waste metabolites and ammonia, a hollow fibre bioreactor recapitulates the homeostatic cellular milieu that will most certainly be absent or poorly-represented in other less in-vivo like culture methods.
Hollow fibre bioreactors have demonstrated complete and uniform post-translational modifications over extended periods of time making them ideal as a way to generate the highest affinity antibodies and difficult-to-express recombinant proteins. Consequently, for diagnostic kit manufacturers who may urgently be seeking ways to enhance monoclonal antibody avidity, hollow fibre cell culture can offer a significant “natural advantage”.
A hollow fibre bioreactor is very compact, easy to install, easily scaleable and very affordable.
Below is a photo of a set up consisting of 4 pumps and 8 hollow fibre cartridges capable of generating 2 grams of mAb per week with a good hybridoma, or 400 mg per week of recombinant protein.
Other advantages include: the ability to operate with a simple and inexpensive media formulation based on DMEM; reduced host cell protein contamination; reduced endotoxin; and the generation of target product that is extremely concentrated.
Suggestions for further reading
Adaptive antibody diversification through N-linked glycosylation of the immunoglobulin variable region: Fleur S. van de Bovenkamp et al.; PNAS, 2018, 115 (8) 1901-1906 [open access]
Implications of Cell Culture Conditions on Protein Glycosylation: M.E.Utlee and R. Easton; BioPharm International 28 (11) 20-25 [open access]
Publications referring to hollow fibre bioreactor
mAbs (hybridoma and recombinant)
Recombinant proteins (including complex “difficult-to-express” proteins and vaccines)
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