Impact of basal media and feeds on CHO cell cultures: a full factorial experiment implicating tryptophan in medium-feed antagonism.

Chinese Hamster Ovary (CHO) cells are the top choice for recombinant protein production in modern biomanufacturing. Selecting the optimal basal media and feeds during the upstream process development is vital for the target product yield and quality, an irrational screening strategy might often result in inefficiencies and development delays. Here we report a full factorial screening of basal media and feeds combinations on four monoclonal antibody expressing CHO cell lines. A statistically significant interaction of the "medium × feed" factors, observed in 48% of the analyzed responses (p < 0.05), confirms their non-additivity and the impracticality of single-factor approaches. We identified a critical combination demonstrating consistently low efficacy in all the analyzed antibodies. The liquid chromatography-mass spectrometry (LC-MS/MS) analysis of its composition revealed, that this combination creates a complex metabolic imbalance: a critical deficiency of tryptophan, a pronounced gradient of taurine (absence in the medium with a high content in the feed) and a similar imbalance of alanine. The findings confirm the need for full-factorial screening when choosing basal media and feeds, and also lay the foundation for a systematic design of culture media within the identified limitations.