Screening and Optimization of Chemically Defined Media and Feeds with Integrated and Statistical Approaches

The majority of therapeutic proteins are expressed in mammalian cells, predominantly in Chinese Hamster Ovary cells. While cell culture media and feed supplements are crucial to protein productivity, medium optimization can be labor intensive and time-consuming. In this chapter, we describe some basic concepts in medium development and introduce a rational and rapid workflow to screen and optimize media and feeds. The major goal of medium screening is to select a base formulation as the foundation for further optimization, but ironically, the most conventional screening method may actually rule out ideal chemically defined medium candidates. Appropriate cell adaptation is the key to identifying an optimal base medium, particularly when cells were originally cultured in serum-free medium containing recombinant proteins and/or hydrolysates. The efficient workflow described herein integrates the optimization of both medium and feed simultaneously using a Design-of-Experiment (DOE) approach. The feasibility of the workflow is then demonstrated with a case study, in which chemically defined medium and feed were optimized in a single fed-batch study using a high-throughput microbioreactor system (SimCell™), which resulted in improving protein titers three- to sixfold.