(727f) Metabolic Flux Analysis Using Isotope Labeled Metabolites to Understand High Lactate Phenotype in a Fed-Batch Cell Culture Process

Empirical approaches have been widely used in cell culture development to identify key variables that improve cell culture process productivity.  These approaches, although useful and in some cases successful, do not lead to an understanding of the underlying mechanism and can result in unintended consequences. Here we report a chemically defined fed-batch antibody production process using CHO cells, which is reproducible with respect to growth and titer but variable in its metabolic phenotype, particularly with respect to glucose consumption and lactate production rates.  In this work we investigate the pathways underlying the variability in the metabolic phenotype by profiling the levels of major extracellular and intracellular metabolites and their mass isotopomers at various phases of the cell culture process.

The insights obtained from the isotopic labeling experiments were used to update and refine a previously developed kinetic model, which was then fitted to the metabolite time course data of the culture. Our results to date show good agreement between the simulated and experimentally measured metabolite profiles as well as overall culture viability and product titer.