Elevated pCO₂ affects the lactate metabolic shift in CHO cell culture processes

Area of Science:

• Biotechnology
• Cellular Metabolism
• Bioprocess Engineering

Background:

• Lactate metabolism shift in Chinese hamster ovary (CHO) cells is crucial for culture longevity and product titers.
• Mechanisms controlling this metabolic shift are not fully understood, with pH and substrate availability previously implicated.
• Elevated partial pressure of carbon dioxide (pCO2) is common in large-scale cell cultures but its metabolic impact is unclear.

Purpose of the Study:

• To investigate the effect of elevated pCO2 on the lactate metabolic shift in CHO cell cultures.
• To elucidate the underlying metabolic mechanisms influenced by high pCO2.
• To provide insights for optimizing large-scale and perfusion cell culture processes.

Main Methods:

• Batch and fed-batch CHO cell cultures were performed under varying pCO2 conditions.
• Metabolic flux analysis was employed to quantify intracellular pathway activities.
• Comparison of metabolic profiles between high and low pCO2 cultures.

Main Results:

• Elevated pCO2 cultures exhibited an absence of the typical lactate metabolic shift observed in control cultures.
• Metabolic flux analysis revealed a correlation between the lactate metabolic shift and the ratio of NADH-producing to regenerating pathways.
• Reduced cellular oxidative capacity was identified as a key factor affected by elevated pCO2.

Conclusions:

• Elevated pCO2 inhibits the lactate metabolic shift in CHO cell cultures.
• The shift is linked to the balance of intracellular NADH pathways, influenced by cellular oxidative capacity.
• Findings suggest pCO2 accumulation may explain unexplained metabolic changes in large-scale fermentations and offer targets for process optimization.