Mammalian fed-batch cultures are widely used in the bio-processing industry to produce recombinant antibodies. However, some limitations in fed-batch systems have been reported such as nutrient depletion; and the accumulation of secondary metabolites which inhibit growth. In Phase 1 process development, poor viability and high lactate production was observed in the terminal stages of a recombinant CHO-IgG fed batch culture. To improve and sustain viable cell densities, metabolomic tools such as Nuclear magnetic resonance (NMR) and Hydrophilic interaction liquid chromatography (HiLIC) were used to probe intracellular and extracellular metabolites. More than 40 components were detected in the spent media and 130 components were detected in intracellular pools, providing us insight to time-dependent cellular metabolism changes during fed-batch culture. Adding back amino acids that were reduced in spent media was able to improve viable cell densities and delaying culture decline. Furthermore, cultures with improved feeds showed a more efficient TCA cycle metabolism as demonstrated by higher levels of s α-ketoglutarate, fumarate and lower levels of lactate production. In addition, the oxygen uptake rate and mitochondrial membrane potential were accessed to examine whether the effects of the additional amino acids were through improved oxidative phosphorylation. Overall, two rounds of feed media design, based on spent media analysis was able to improve productivity yields by another 50%, with minimal effects to product quality. This process was developed at the 2L scale and successfully scaled up to 500L pilot plant to demonstrate robustness.

Application of metabolomic analysis to systematically design fed-batch media for process improvement

249th National Meeting (2015)

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