Micro scale, high throughput perfusion technology is under-developed and not widely utilised in academic or industrial settings for the development of CHO based mAb bioprocesses. Work within this thesis highlights the design and characterisation of a sedimentation method of cell retention and its application in a fed batch designed ambr® micro scale bioreactor system.

The work identifies periods of up to one hour required to perform the necessary sedimentation and media exchanges. In comparison, bench scale equivalent culture reaches comparable cell densities as their microscale counterparts, highlighting suitability for screening development activities in this high throughput system that was previously unattainable with the high media demands of a perfusion process. The comparison of scales highlighted a lag in growth between the two perfusion methods that was thought to be a combination of periods of uncontrolled parameters at microscale (while cells were undergoing sedimentation) and small but frequent removal of cells from the microscale cultures, as retention efficiency was below 100%.

In addition to this, the execution of the perfusion method highlighted CHO cell insensitivity to high levels of pH and DO variation that would normally elicit a severe decline in culture performance. Potential control strategies that focused on cellular sensitivity at inoculation were investigated and their application highlighted. Whilst applicable to fed batch cultures, it is in perfusion (or other continuous methods) where a significant benefit will be realised as they can attain high performance through tight control during inoculation and allowing flexibility during extended periods of cultivation.

Combining the functionality and capacity offered by the sedimentation method in the ambr® system with the highlighted potential control strategy for perfusion equips the bioprocessing industry to explore the benefits of perfusion culture to meet increasing global demand for mAbs.