Rapid and flexible scale-down media development and optimization for perfusion culture

Conference Dates

May 6-11, 2018


Perfusion culture is steadily gaining interest due to advantages such as higher cell densities, increased flexibility, higher volumetric output, decreased product retention times, and more consistent product. Perfusion culture systems are drastically different than fed-batch cultures as they allow bioreactors to continuously run for prolonged periods of time by constantly feeding fresh media while removing spent media. This drastic process difference means that typical fed-batch medium is not optimal for perfusion culture. Instead, perfusion culture media is most optimal when it fits within culture process constraints such as vessel volume exchanges per day. Irvine Scientific has rapidly developed custom media for a specific perfusion culture process that resulted in a significant increase in viable cell density and antibody titer. The custom media was developed in the following steps: (1) identification of initial base media, (2) development and verification of a scale-down perfusion model, (3) optimization of media components, and (4) parsing down extraneous components while maintaining growth and titer. First, a media survey was conducted in batch cultures to determine an initial basal media composition to further refine. From a panel of over 20 different media, top candidate media were selected based on improved viable cell density, viability, titer, and glycan profile over the control medium. Next, a scale-down perfusion model was developed and validated using the control medium. Mini bioreactor tubes were used as culture vessels and daily perfusion was conducted by centrifugation, aspiration, and replenishment with fresh medium. Antibody glycan profiles from the scale-down perfusion model matched profiles from large-scale bioreactor perfusion cultures, thus validating the use of this scale-down model. Although this system is not controlled, the pH was monitored offline and stayed within range. The candidate media were evaluated in the scale-down perfusion model and the top prospects in terms of titer and viable cell density were chosen for further development by changing the composition of amino acids, metals, and other components. Lastly, amino acid concentrations were further optimized while parsing down extraneous components according to spent media analysis from the previous experiment. The top medium resulted in a significant increase in viable cell density and titer compared to the original control medium. This process created a custom medium for perfusion culture that significantly increased viable cell density and antibody titer while maintaining a desired glycan profile. The media development process in scale-down perfusion cultures was rapid and took about 10 weeks. Development in controlled, scale-down bioreactor systems may be more costly and take longer as procedures, protocols, and methods first need to be transferred and verified. This scale-down perfusion model, while manual, is an easy and flexible way to develop perfusion medium with efficient throughput. Currently, the medium is being verified in perfusion bioreactors and can be further improved. In the future, we will investigate increasing the productivity by concentrating the culture medium while decreasing the volume vessel exchanges.

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