Low CO2 partial pressure steers CHO cells into a defective metabolic state.

Purpose: The accumulation of carbon dioxide during large-scale culture of animal cells brings adverse effects, appropriate aeration strategies alleviate CO₂ accumulation while improper reactor operation may lead to the presence of low CO₂ partial pressure (pCO₂) condition as occurs in many industrial cases. Thus, this study aims to reveal the in-depth influence of low pCO₂ on Chinese Hamster Ovary (CHO) cells for providing a reference for design space determination of CO₂ control with regard to the Quality by Design (QbD) guidelines. Methods and results: The headspace air over purging caused the ultra-low pCO₂ (ULC) where the monoclonal antibody production as well as the aerobic metabolic activity were reduced. Intracellular metabolomics analysis indicated a less efficient aerobic glucose metabolic state under ULC conditions. Based on the increase of intracellular pH and lactate dehydrogenase activity, the shortage of intracellular pyruvate could be the cause of the deficient aerobic metabolism, which could be partially mitigated by pyruvate addition under ULC conditions. Finally, a semi-empirical mathematical model was used to better understand, predict and control the occurrence of extreme pCO₂ conditions during the cultures of CHO cells. Conclusion: Low pCO₂ steers CHO cells into a defective metabolic state. A predictive relation among pCO₂, lactate, and pH control was applied to get new insights into CHO cell culture for better and more robust metabolic behavior and process performance and the determination of QbD design space for CO₂ control. [ABSTRACT FROM AUTHOR]