Characterizing the preparation of a concentrated nutrient feed solution for a large-scale cell culture process

Fed-batch mammalian cell culture processes frequently employ concentrated and complex media and feeds during the production phase. Though significant efforts are undertaken to characterize the large-scale bioreactor with respect to its control parameters, similar efforts are not commonly undertaken to characterize the feed preparation process. During the characterization of a commercial cell culture process using elements of Quality-by-Design (QbD) principles, we identified the complex nutrient feed solution preparation as an important step and temperature, mixing time, and mixing intensity were identified as factors impacting this unit operation via a systematic risk assessment. To best simulate the large-scale feed preparation process, a 3L model was developed to determine the impact of the feed preparation conditions. Feed preparation parameters were characterized and the solutions generated were analyzed using various analytical methods, a filterability assessment, and cell culture use tests that included evaluation of culture performance and relevant product quality attributes. Based on the data from the characterization studies, appropriate ranges for an allowable multivariate operating space for large scale feed preparation were determined. These studies demonstrated how the preparation of complex nutrient feed solutions could be modeled and characterized to ensure the success of a cell culture manufacturing campaign.