(518f) Optimization of a Mammalian Cell Perfusion Culture in Productivity and Product Quality

Contact person: Moritz Wolf, moritz.wolf@chem.ethz.ch

The continuous production of therapeutic proteins using mammalian cell perfusion cultures combines several advantages compared to traditional batch-wise operations applied in industry. So far, this processing mode has been used in particular for the production of labile proteins. However, the achievement of long-term stable cultures, higher productivities, and enhanced product quality are pathing the way to a more general application of continuous cell perfusion cultures [1]. Continuous supply of fresh nutrients as well as removal of waste metabolites combined with the retention of cells allow steady state cultures at very high cell densities [2]. Stable and robust operations further minimize product heterogeneities and allow the simple modulation of critical quality attributes.

This study aimed at the optimization of productivity and product quality in a stirred tank perfusion bioreactor (3) by tuning key cell culture variables for a CHO cell line producing a monoclonal antibody (mAb). The applied sequential screening approach of most influential process parameters including, media composition, cell specific perfusion rate (CSPR), and temperature allowed a rapid evaluation of multiple operating points. While varying one parameter at a time, measurements of extra- and intracellular metabolites, product concentration as well as quality attributes were used to characterize their effect on cellular growth, productivity and product quality at steady state.

The tuning of key cell culture parameters led to a superior performance of the perfusion culture compared to the established fed-batch platform. Especially, the decrease of the CSPR resulted in higher product amounts. Whereas the optimization of media composition lead to an increase of cell density while maintain perfusion rate low. At steady state operation of the perfusion bioreactor naturally occurring microheterogeneities of the produced mAb (e.g. N-linked glycosylation pattern and charge isoforms) were reduced compared to fed-batch runs. Low byproduct levels and the decoupling of tested variables allowed the deliberate shaping of these attributes. Overall, this study highlights the potential of mammalian cell perfusion cultures for the production of therapeutic proteins.

Literature

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[2] M.-F. Clincke, C. Mölleryd, Y. Zhang, E. Lindskog, K. Walsh, V. Chotteau, Very high density of CHO cells in perfusion by ATF or TFF in WAVE bioreactorTM. Part I. Effect of the cell density on the process., Biotechnol. Prog. 29 (2013) 754â??767.

[3] D. Karst, E. Serra, T. Villiger, M. Soos, M. Morbidelli, Characterization and comparison of ATF and TFF in stirred bioreactors for continuous mammalian cell culture, Biochem. Eng. J. 110 (2016) 17-26.