Impact of preparation pH and temperature on amino acid stability of highly concentrated cell culture feed media

BACKGROUND: The stability of amino acids (AAs) in a highly concentrated cell culture medium is affected by medium preparation and storage conditions. Variability in the concentration of medium components (including AAs) can influence cell culture performance and product quality attributes. RESULTS: In this report, the impact of preparation pH, preparation temperature, and storage temperature was evaluated on the stability of 16 AAs in a highly concentrated cell culture feed medium. Optimizing the medium pH enabled an increase in the initial feed medium concentration by 30% plus 3.9 g L⁻¹ tyrosine with no observed precipitation after 28 days. Up to 6.0 g L⁻¹ tyrosine can be supplemented in the medium at ~pH 10 without precipitation. Moreover, preparing the medium at 40–50 °C prevented precipitation during storage at 4–8 °C. A slight negative impact on AA stability during this high-temperature preparation was observed, but this impact was negligible relative to the AA degradation observed during extended storage of media prepared at 37 °C. The optimal preparation pH and temperature allowed the concentrated medium to be stored at 4–8 °C with minimal AA degradation and without precipitation. These discoveries were further supported by principal component analysis of AA profile similarity before and after storage at different pH and temperature conditions. CONCLUSION: This study describes the medium preparation parameters to improve AA stability and mitigate precipitation issues. The optimization strategy will facilitate the development of robust cell culture production processes.