By Franziska Janke, Lars Kober and Robert Glaser
Scaling up bioprocesses, from a small development scale to a pilot and production scale, is a fundamental part of process development in the biopharmaceutical industry. To reproduce the performance of the process while increasing the volume of work, the optimal cellular environment must be replicated.
Scaling up is often accompanied by a process transfer to bioprocess systems with other properties, such as different geometries and engineering parameters. Depending on the scaling strategy, parameters such as mixing time, oxygen transfer and power input must be taken into account. Since it is usually not possible to keep all parameters when scaling, bioengineers must assess which are the most critical. Among the most important aspects of scaling are the mass transfer of oxygen and the concentration of dissolved oxygen (DO) in the culture medium. The mass transfer of oxygen depends mainly on the air bubbling system, the gassing rate, the oxygen concentration, the wheels selected, their settings, the power absorbed and the gas dispersion properties.
In this study, we extended a 1 L CHO cell culture bioprocess using a DASGIP® parallel bioreactor system to 5 L using a BioFlo® 320 bioprocess control station. To develop a scaling strategy , we partially compared the power number and the density transfer coefficient (kLa) of the bioreactors. The results show that the kLa value can be used as a suitable scaling criterion from small to bench scale.