Analysis of Chinese hamster ovary cell metabolism through a combined computational and experimental approach

Abstract

Optimization of cell culture processes can benefit from the systematic analysis of experimental data and their organization in mathematical models, which can be used to decipher the effect of individual process variables on multiple outputs of interest. Towards this goal, a kinetic model of cytosolic glucose metabolism coupled with a population-level model of Chinese hamster ovary cells was used to analyse metabolic behavior under batch and fed-batch cell culture conditions. The model was parameterized using experimental data for cell growth dynamics, extracellular and intracellular metabolite profiles. The results highlight significant differences between the two culture conditions in terms of metabolic efficiency and motivate the exploration of lactate as a secondary carbon source. Finally, the application of global sensitivity analysis to the model parameters highlights the need for additional experimental information on cell cycle distribution to complement metabolomic analyses with a view to parameterize kinetic models.

Fig. 1

Topological model compartmentalization

Fig. 2

Metabolic map of cytosolic glucose catabolism in CHO cells

Fig. 3

Overall strategy for modeling

Fig. 4

Metabolic flux distribution for exponential phase in CHO cells. The open flux from G6P goes toward nucleotide sugar synthesis, that from 3PG toward serine metabolism, the open flux from DHAP goes toward glycerol synthesis, and that from Ru5P goes towards nucleotide synthesis

Fig. 5

Comparison of model simulation results to experimental data for batch cell culture for a viable cell concentration, b Extracellular glucose concentration, c extracellular ammonia concentration, d extracellular lactate concentration

Fig. 6

Comparison of model simulation results to experimental data for fed-batch cell culture for a viable cell concentration, b Extracellular glucose concentration, c extracellular lactate concentration

Fig. 7

Comparison of model simulation results to experimental data for fed-batch cell culture for a intracellular glucose concentration, b intracellular lactate concentration

Fig. 8

Parameter sensitivity indices for viable cell concentration as the objective function for a day 3, and b day 6 of batch cell culture

Fig. 9

Parameter sensitivity indices for extracellular glucose concentration as the objective function for a day 3, and b day 6 of batch cell culture

Fig. 10

Parameter sensitivity indices for extracellular lactate concentration as the objective function for a day 3, and b day 6 of batch cell culture

Fig. 11

Parameter sensitivity indices for intracellular glucose as the objective function for a day 3, and b day 6 of batch cell culture

Fig. 12

Simulation results for viable cell concentration under different initial extracellular lactate concentrations under batch cell culture. The arrow signifies an increasing starting concentration of lactate extracellularly