October 18-21, 2015
To accelerate cell culture process development, most companies have validated scale-down models of their pilot and manufacturing scale bioreactors. Advancing such mimics to even smaller scales requires the large scale engineering environment to be accurately recreated. Here we describe a single-use microwell methodology that accurately reproduces not only cell growth kinetics but also key attributes related to product quality and broth processability.
The μ24 miniature bioreactor system enables system level control of agitation (by orbital shaking), with individual well control of pH, DO and temperature. Two distinct plate types are investigated, allowing for either headspace or direct gas sparging. An engineering characterisation was performed evaluating fluid mixing, gas transfer capacity and the dispersed gas phase. Cell culture is investigated using a model CHO DG44 cell line expressing a whole IgG1 mAb .
In addition, this work describes scale-up of μ24 results to conventional laboratory scale stirred tank bioreactors (2L) and use of the device for selection of robust and scaleable cell lines through evaluation of product quality. The ‘broth quality’ is also evaluated for primary clarification efficiency using an Ultra Scale-Down (USD) depth filtration rig that requires quantities of material compatible with those available from the miniature bioreactors.
Apparent kLa values ranged between 3–22 hr-1 and 4–53 hr-1 for headspace aeration and direct gas sparging respectively. Mixing times were generally in the range 1–13 seconds and decreased with increasing shaking frequency (500–800 rpm). Direct gas sparging also helped to reduce tm values.
Cultures performed with headspace aeration showed the highest VCD and antibody titres, whereas those operated with direct gas sparging showed cell growth kinetics and product titres that were more comparable to those found in a conventional 2L stirred bioreactor. Initial results also indicate that key product and broth processability attributes are maintained making the combination of μ24 and USD technologies useful tools in ‘Quality by Design’ driven cell culture process development.
 Betts, J.P.J., Warr, S., Finka, G., Uden, M. Town, M., Janda, J.M., Baganz, F. and Lye, G.J. (2014). Impact of aeration strategies on fed-batch cell culture kinetics in a single-use 24-well miniature bioreactor. Biochem. Eng. J., 82: 105-116.