On-line monitoring of responses to nutrient feed additions by multi-frequency permittivity measurements in fed-batch cultivations of CHO cells

• Published in: Cytotechnology (Dordrecht) Vol. 62; no. 2; pp. 121 - 132
• Main Authors: Ansorge, Sven, Esteban, Geoffrey, Schmid, Georg
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.04.2010; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Batch culture; Batch processes; Biochemistry; Biological and medical sciences; Biomass; Biomedicine; Biotechnology; Cell culture; Cell lines; Cell size; Characteristic frequency; Chemistry; Chemistry and Materials Science; CHO cell culture; Dielectric properties; Fed-batch; Fundamental and applied biological sciences. Psychology; Glucose; Metabolism; Metabolites; Monoclonal antibodies; Nutrient availability; Original Research; Permittivity; Physiological state; Physiology; Switzerland; Germany; Fed-batch; CHO cell culture; Permittivity; Physiological state; Characteristic frequency; Cell culture; Nutrient; Physiology; Semicontinuous; CHO cell line; Monitoring
• ISSN: 0920-9069; 1573-0778
• DOI: 10.1007/s10616-010-9267-z

Changes in the nutrient availability of mammalian cell cultures are reflected in the β-dispersion parameter characteristic frequency (f C ) and the on-line dual frequency permittivity signal. Multi-frequency permittivity measurements were therefore evaluated in fed-batch cultivations of two different CHO cell lines. Similar responses to nutrient depletions and discontinuous feed additions were monitored in different cultivation phases and experimental setups. Sudden increases in permittivity and f C occurred when feed additions were conducted. A constant or declining permittivity value in combination with a decrease in f C indicated nutrient limitations. f C correlated well with changes in oxygen uptake rate when cell diameter remained constant, indicating that metabolic activity is reflected in the value of f C . When significant cell size changes occurred during the cultivations, the analysis of the β-dispersion parameters was rendered complex. For the application of our findings in other systems it will be hence required to conduct additional off-line measurements. Based on these results, it is hypothesized that multi-frequency permittivity measurements can give information on the intracellular or physiological state in fed-batch mode. Similar observations were made when using different cell lines and feeding strategies, indicating that the findings are transferable to other cell lines and systems. The results should lead to an improved understanding of routine fed-batch processes. Additional studies are, however, required to explore how these observations can be used for fed-batch process development and optimization.