Metabolomics-driven investigation of novel growth inhibitors in CHO cell bioprocessing

Abstract

Biopharmaceuticals are a critical class of medicines used to treat many serious diseases. Cultured mammalian cells are used to produce many biopharmaceuticals in bioprocesses, with Chinese hamster ovary (CHO) cells being the most common host cell type utilised for this purpose. To improve biopharmaceutical production efficiency and reduce associated costs, CHO cell bioprocess optimisation is an important focus for biopharmaceutical manufacturers. Metabolomics is a systems biology tool which can be utilised to make rationally informed improvements to CHO cell bioprocesses, by providing insights to the suite of small molecules consumed and produced by CHO cells during a bioprocess. Metabolomics can be used to investigate growth-inhibitory CHO cell metabolites produced during a bioprocess which cause deleterious effects on bioprocess efficiency, which is a growing area of interest to optimise CHO cell bioprocesses and the purpose of this thesis. A monoclonal producing CHO cell line was grown in a fed-batch bioprocess and analysed by a multiplatform metabolomics approach to generate a metabolic snapshot under standard platform bioprocessing conditions combining liquid chromatography ion mobility spectrometry mass spectrometry (LC-IMS-MS) and proton nuclear magnetic resonance spectroscopy (1H NMR) metabolomics. This was used to suggest and investigate novel growth-inhibitory metabolites in scale-down experiments which identified a panel of growth inhibitory organic acids accumulating across the fed-batch bioprocess. A feed medium modulation strategy was implemented to investigate whether reducing nutrient precursors for production of these organic acids could increase cell-growth or recombinant protein productivity. Additionally, the utility of an on-line mass-spectrometry metabolomics system was investigated for monitoring live CHO cell bioprocesses. Taken together, these results highlight the applicability of metabolomics to generate a holistic understanding of CHO cell metabolism and to form knowledge driven hypotheses for enhanced biopharmaceutical production. This work lays groundwork for subsequent optimisation of an industrially relevant CHO cell bioprocess platform with a focus on addressing CHO cell growth inhibitory metabolites produced during biopharmaceutical production processes.