(175v) Comparison of CHO Cell Cultures Performance in Shaken and Spinner Flasks Bioreactors at the Same Value of Volumetric Mass Transfer Coefficient

Monoclonal antibodies (mAbs) are the basis of many drugs for the treatment of high-impact diseases such as asthma, rheumatoid arthritis, and various types of cancer. Therefore, mAb global sales are projected to $ 125 billion by 2020. Currently, CHO cells are the most employed cell line for producing mAbs, because of their efficient posttranslational processing of complex proteins. At upscaling CHO cultures, oxygen delivery is considered a large limitation, mainly due to the sparse solubility of oxygen in culture media. As culture volume increases, more forceful operation conditions are required for achieving an adequate Oxygen Transfer Rate (OTR). Considering that culture medium is perfectly mixed, OTR can be defined as the contribution of two terms, the volumetric mass transport coefficient (kLa) and the mass transfer driving force, that is, the difference of concentrations between the liquid surface and the average in liquid bulk.

Screening processes are commonly carried out in small vessels, which are stirred by a shaker. Nevertheless, industrial cultures of CHO cells are widely performed in stirred tanks. Since these bioreactor configurations are different in terms of shape and shaking, it is important to set a parameter as scale-up guideline, which it is supposed to be maintained in the different devices, for achieving the same results through the scales.

In this work, a parental CHO cell line was cultured at different values of kLa to evaluate the pertinence of kLa as scale-up parameter. Cultures were performed in 60ml Erlenmeyer- and 100ml Spinner-Flasks, adapted for online dissolved oxygen measurement. Response variables were cell, glucose, lactate, and ammonia concentration, osmolality and pH. Additionally, free lactate dehydrogenase (LDH) concentration was quantified as necrosis death indicator. Results show the effect of kLa on CHO metabolic behavior. Oxygen limitation was presented in cultures with the lowest kLa value at higher cell concentration than 1×106 cell ml-1, whereas at higher kLa, carbon source limitation was first evidenced. At highest kLa values, LDH was rapidly liberated, and higher cell concentrations were achieved, though. This strategy may be used for further screening and scale-down studies.