(67d) Energy-Based Medium Design for Mammalian Cell Fed-Batch Cultures

Mammalian cell cultures are the main industrial platform for the production of high-value biologics, such as monoclonal antibodies (mAb) [1]. One way to reduce operational costs is by maximising mAb yield and cell growth whilst minimising cell culture medium expenditure. Current optimization strategies are typically empirical requiring a multitude of expensive, intensive and time consuming experiments. Model-based optimization approaches seek to reduce unnecessary experimentation. Previously, we have applied model-based optimization methods to identify feeding regimes to maximize mAb titter in GS-NS0 cultures limited only on glucose and glutamate supply while neglecting the exhaustion of other essential amino acids [2]. In addition, culture medium design has been based on stoichiometric balances considering only cell composition [3] and metabolite profiling where the medium was designed based on the exhaustion of a limited number of nutrients [4]. Alas, the above-mentioned studies neglect the energy requirements of the cell not only for maintenance and proliferation but also for mAb production.

Herein, a novel predictive model for GS-NS0 cells producing cB72.3 mAb has been developed considering cell and product composition as well as cellular energy requirements for maintenance, proliferation, and mAb production. The development of this model follows the framework described in [5] and describes growth kinetics, metabolism, mAb secretion and the production/consumption of ATP based on glucose and 15 amino acid energy metabolic pathways. The full range of the model parameters was subjected to Global Sensitivity Analysis (GSA) to identify the significant parameters that were then estimated from specifically-designed batch experiments. Subsequently, the validated model was utilised to design a low cost supplemental medium for the implementation of an optimized fed-batch strategy which increased production by 60% and extended viability and culture longevity by 24 hrs. As a result of this feeding strategy, nutrient and ATP concentrations were controlled in a tight range without accumulation. The successful coupling of cell and product composition with energy requirements has enabled the development of a tailored medium composition reducing operational costs whilst maximising production. This integrated model-based platform, which is experimentally validated, presents a cost-effective and efficient approach for media development and upstream optimisation of a wide range of biopharmaceutical products.

References

1. Zhu, J., Mammalian cell protein expression for biopharmaceutical production. Biotechnology advances. 2012. 30(5): p.1158-1170.
2. Kiparissides,A., Kountinas,M., Kontoradvi,C., Mantalaris, A., Pistikopoulos, E.N. â??Closing the loopâ?? in biological systems modeling â?? From the in silico to the in vitro. Automatica. 2011. 47(6): p.1147-1155.
3. Xie, L, Wang, D.I.C. High Cell Density and High Monoclonal Antibody Production Through Medium Design and Rational Control in a Bioreactor. Biotechnology and Bioengineering.1996. 51: 725-729.
4. Sellick, C.A., Croxford,A.S., Maqsood,A.R., Stephens, G., Westerhoff,H.V., Goodacre,R., Dickson, A.J. Metabolite Profiling of Recombinant CHO Cells: Designing Tailored Feeding Regimes That Enhance Recombinant Antibody Production. Biotechnology and Bioengineering. 2011. 108 (12): 3025â??3031.
5. Kiparissides,A., Pistikopoulos,E.N., Mantalaris,A. On the model-based optimization of secreting mammalian cell (GS-NS0) cultures. Biotechnology and Bioengineering. 2015. 112: 536â??548.