Shear protectants such as Poloxamer 188 are routinely used in mammalian cell culture to protect cells from the hydrodynamic conditions of sparged bioreactors. As industry continues to push culture densities higher to maximize product yield, higher aeration levels are required. Additional aeration leads to harsher environments for cells, leading to the need for improved shear protection strategies to minimize cell damage. In this project, we demonstrate the use of a novel concentric cylinder mixer (CCM) assay to quantify the relative shear sensitivity of mAb producing Chinese Hamster Ovary (CHO) cell lines in production bioreactors. The CCM assay is based on release of lactase dehydrogenase (LDH), an enzyme marker for cellular damage. Compared with other methods to characterize shear sensitivity, the CCM assay requires low sample volume (~5 mL) and minimal processing time (~5 minutes). Results indicate that cell shear sensitivity dramatically increases upon reaching the stationary phase of the cell cycle, coinciding with viability decline and LDH increase in the bioreactor. This increased sensitivity may be a result of depletion of shear protectant, accumulation of waste in the medium, or physiological changes in the cell. With a simple shift in shear protectant concentration, we achieved increased harvest viability resulting in decreased cellular debris, decreased foam stability, and a two-fold reduction in LDH upon harvest. The application of this novel shear assay can aid in optimizing process parameter set points, enhancing medium formulations for process robustness, and also for the selection of shear resistant cell lines for process development.

Novel shear assay for increasing chinese hamster ovary cell culture robustness in biomanufacturing

253rd National Meeting (2017)

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