Earlier media formulations included serum addition, which posed high risk of virus contamination. Subsequently, serum was replaced by variety of yeast and plant hydrolysates to maintain growth and productivity performance. Serum and hydrolysates introduce a number of unidentified components into the medium formulation which cannot be properly quantified. This introduces lot-to-lot variability and makes it difficult for the scientist to systematically develop fed-batch processes to improve productivity.
Chemically defined media formulations are highly desirable as each component of the formulation is known and can be readily quantified allowing rational design of feed formulation to improve performance of the cell culture processes.
Efforts within the cell culture group at GSK led to the identification of a suitable chemically-defined medium formulation capable of supporting growth of several host and transfected cell lines with two different expression systems (DHFR and GS) with high degree of success. The lead formulation was identified through Design of Experiments (DOE) and further refinement of specific components. The final formulation has shown equivalent or better performance than commercially available formulations.