Metabolic Network Modelling of Chinese Hamster Ovary (CHO) Culture Bioreactors Operated as Microbial Cell Factories

Abstract

Chinese hamster ovary (CHO) epithelial cells are one of the most used therapeutic medical lines for the production of different biopharmaceutical drugs. They have a high consumption rate with a fast duplication cycle that makes them an ideal biological clone. The higher accumulated amounts of toxic intracellular intermediates may lead to lower organism viability, protein productivity and manufactured biosimilar, so a careful optimal balance of medium, bioreactor operational parameters and bioprocess is needed. A precise phenomenological knowledge of metabolism's chemical transformations can predict problems that may arise during batch, semi-continuous fed batch and continuous reactor operation. For a better detailed understanding (and relations), future performance optimization and scaling, mechanistic model systems have been built. In this specific work, the main metabolic pathways in mammalian structured CHO cultures are reviewed. It starts with organic biochemical background, controlling associated phenomena and kinetics, which govern the sustaining conversion routes of biology. Then, individual turnover paths are described, overviewing standard mathematical formulations that are commonly applied in engineering. These are the core of black box modeling, which relates the substrates/products in a simplified relationship manner. Moreover, metabolic flux analysis (MFA)/flux balance analysis (FBA), that are traditionally characterizing mechanisms, are presented to a larger portion extent. Finally, similarities are discussed, illustrating the approaches for their structural design. Stated variables' equations, employed for the description of the growth in the controllable environmental conditions of a vessel, the researched reaction series of proliferating dividing CHO population, joint with the values of maximal enzymatic activity, and solutions are outlined. Processes are listed in a way so that a reader can integrate the state-of-the-art. Our particular contribution is also denoted.

Deciphering Metabolic Pathways in High-Seeding-Density Fed-Batch Processes for Monoclonal Antibody Production: A Computational Modeling Perspective

“…The switch in lactate metabolism from its production as part of an inefficient overflow metabolism to its consumption in a more efficient metabolic phase, for example, is a well-known and desired phenomenon that is not yet fully understood mechanistically [18]. Several hypotheses on the cause of this phenomenon exist (see e.g., [18][19][20]) and were included in some models with different strategies based on the introduction of a redox variable [10] or switching function [21], the usage of two different kinetics for the lactate dehydrogenase [7], or simply making the reaction reversible [22].…”