Early viability decline and low titer were observed in a clinical-scale CHO cell culture manufacturing process, following modifications to the working volume. Additionally the dissolved oxygen profile did not match historical performance. However, differences in performance were not observed following similar modifications to the process for a second molecule expressed in a different CHO cell line. It was hypothesized that the increased proximity of the impeller to the gas-liquid interface contributed to a higher shear environment inside the reactor. High shear has the potential to negatively impact CHO process performance. The ambr250® was selected to investigate the impact of hydrodynamic stress on cell culture performance. Conditions including impeller type, agitation, sparging, and proximity of the impeller to the gas-liquid interface were evaluated; peak cell density, viability, titer, and key product quality attributes were all measured as outputs of the culture response to shear. While impeller type, agitation, and sparging all had observable impact on process performance, placing the impeller near to the gas-liquid interface resulted in trends similar to the poor performance at the clinical scale. Subsequent runs at this scale with a greater higher working volume were successful. A model combining high agitation and impeller exposure in the high throughput system was established based on this data. Multiple cells lines were tested in this high throughput model; the impact of impeller location was not consistent between cell lines, suggesting that sensitivity to shear is cell line specific. This model provides a high throughput tool to screen clones during selection that are best suited for future scale up manufacturing. Understanding of process shear sensitivity using this model has been taken into account to successfully transfer the process to a &gt;10,000L scale bioreactor.

Development of a high throughput scale-down model to mitigate shear sensitivity risk in cell culture process scale-up

2019 Spring National Meeting

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