Scale-up analysis for a CHO cell culture process in large-scale bioreactors

Area of Science:

• Biotechnology
• Biochemical Engineering
• Cell Culture Technology

Background:

• Bioprocess scale-up is critical for biotechnology, involving challenges in mammalian cell culture.
• Key scale-up factors include mixing time, oxygen transfer, and carbon dioxide removal.

Purpose of the Study:

• To evaluate scale-up issues in 5,000-L bioreactors using cell-free mixing studies.
• To assess the impact of bioreactor configuration on critical process parameters.

Main Methods:

• Cell-free mixing studies were conducted in 5,000-L production scale bioreactors.
• Comparison with bench scale (5- and 20-L) bioreactors.
• Dual probe technique used to detect gradients.

Main Results:

• The 5,000-L bioreactor showed poorer oxygen transfer, longer mixing times, and reduced CO2 removal compared to smaller scales.
• Oxygen transfer limits viable cell density to 7 x 10^6 cells/mL.
• Potential for pH and dissolved oxygen gradients in the 5,000-L bioreactor.

Conclusions:

• Empirical equations predict improved oxygen transfer and CO2 removal by increasing bottom air sparging over power input.
• Bulk mixing is challenging in large, fed-batch bioreactors.
• Optimization of engineering parameters is crucial for mitigating scale-up risks.