CO(2) in large-scale and high-density CHO cell perfusion culture

Area of Science:

• Biotechnology
• Cell Culture Engineering
• Bioprocess Optimization

Background:

• Chinese Hamster Ovary (CHO) cell cultures are crucial for biopharmaceutical production.
• Maintaining optimal dissolved oxygen (DO) and carbon dioxide (CO2) levels is critical for maximizing cell productivity in perfusion reactors.
• High pCO2 levels (>150 mm Hg) have been observed to inhibit CHO cell growth and reduce productivity.

Purpose of the Study:

• To determine the optimal pCO2 range for maximizing productivity in CHO perfusion cultures.
• To measure oxygen utilization and CO2 production rates in CHO perfusion cultures.
• To develop a method for measuring mass transfer coefficients and a model to predict the effect of bubble size on gas transfer rates.

Main Methods:

• Measurements of oxygen utilization and CO2 production rates for CHO cells in perfusion culture.
• Development of a method to directly measure mass transfer coefficients for oxygen and carbon dioxide.
• Development of a model to predict the effect of bubble size on oxygen and CO2 transfer rates.

Main Results:

• Maximal productivity in CHO perfusion cultures was achieved when pCO2 was maintained between 30-76 mm Hg.
• Oxygen utilization rate was measured at 5.55×10(-17) mol cell(-1) sec(-1) and CO2 production rate at 5.36×10(-17) mol cell(-1) sec(-1).
• A low CO2 removal efficiency limited culture density to 2.4×10(6) cells/mL with pure oxygen sparge at 0.002 VVM.
• Using 2-3 mm bubbles with pure oxygen in headspace and sparge can minimize sparging rate and match gas transfer to metabolic rates.

Conclusions:

• Maintaining pCO2 in the range of 30-76 mm Hg is essential for maximizing CHO cell productivity.
• Optimizing bubble size and gas sparging strategy is critical for efficient gas transfer and achieving high cell densities.
• The developed model and methods can aid in optimizing bioreactor conditions for enhanced biopharmaceutical production.