Evaluation of the effect of chronic hydrodynamical stresses on cultures of suspensed CHO‐6E6 cells

Abstract

The effect of hydrodynamic forces on animal cell cultures, while extensively studied, still lacks significant, fundamental understanding. A previous manuscript reported on the acute exposure of CHO cells to hydrodynamic forces in a second generation convergent-divergent microfluidic device (Mollet et al., 2007). In this study, the use of this device is extended in a proof of concept system in which suspended animal cells, grown in a typical bioreactor, are subjected to chronic exposure of moderately high levels of hydrodynamic forces by way of a continuous recycle loop between the bioreactor and the microfluidic device. A strain of CHO cells (CHO-6E6) was grown in a batch culture under controlled pH, temperature, and dissolved oxygen conditions. At mid exponential stage of growth in the bioreactor the recycle flow was initiated. The cells either stopped growing or started dying at EDR values that were significantly lower (one to two orders of magnitude) than those previously reported to kill cells from a single, acute exposure. These observations allow further refinement in the design of bioprocess equipment since it provides a more accurate threshold, above which one does not want to subject animal cells to continuous exposure to specific levels of hydrodynamic forces.

Scale-down studies for assessing the impact of different stress parameters on growth and product quality during animal cell culture

“…The loop was essentially as described earlier (Godoy-Silva et al, 2009a;2009b) antibody product quality was assessed using a Genentech protocol in a similar set of ways to that set out above. It should be noted that with the techniques employed to assess quality, it would be difficult to detect any changes in charge profiles associated with sialylation.…”

“…Consistency of glycoform is a major consideration when assessing protein quality for therapeutic purposes (Jenkins, 2007;Godoy-Silva et al, 2009a;2009b). As can be seen, the small variation in glycoforms between the differing experimental conditions to which the cells were exposed is quite random and typical of that found in industrial historical data.…”

“…Overall, it was decided to try circulation with a syringe pump as was used in the previous work by Godoy-Silva et al, (2009a;2009b) when using the extensional flow device.…”

“…To further explore such issues, Chalmers and co-workers (Godoy-Silva et al, 2009a, 2009b ). However, in the first case, cell growth was inferior compared to controls without recirculation (Godoy-Silva et al, 2009a); and in the second, it was product quality (Godoy-Silva et al, 2009b).…”

“…The aim was to clarify the earlier work of Godoy-Silva et al (2009a;2009b) on the impact of laminar stresses on process performance and product quality using two Genentech production CHO cells lines. In addition, further studies with these two lines were conducted in a bioreactor agitated by dual Rushton turbines at turbulent mean specific energy rates, T ε up to 1000 W/m 3 .…”