The relation between growth phases, cell volume changes and metabolism of adherent cells during cultivation

• Published in: Journal of biotechnology 2013-04, Vol.164 (4), p.489-499
• Main Authors: Rehberg, M., Ritter, J.B., Genzel, Y., Flockerzi, D., Reichl, U.
• Format: Article
• Language: English
• Subjects: Animals; Cell Adhesion - physiology; Cell Count; Cell Culture Techniques - instrumentation; Cell Culture Techniques - methods; Cell growth phases; Cell Growth Processes - physiology; Cell number delay; Cell Size; Cell volume; Computer Simulation; Dogs; Female; Glucose - metabolism; Glutamine - metabolism; Madin Darby Canine Kidney Cells; Mathematical model; MDCK cell; Models, Biological; Reproducibility of Results
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2013.01.018

[Display omitted] ► We develop a mathematical model for adherent cell growth in numbers and size. ► The model is suited to simultaneously describe three independent cultivations. ► We evaluate cell growth phases in terms of cell number and cell volume increase. ► Precise estimation of parameters reveals time dependent demands for substrates. ► Cellular glucose uptake correlates with glucose 6-phosphate dynamics. In biotechnology, mathematical models often consider changes in cell numbers as well as in metabolite conversion to describe different cell growth phases. It has been frequently observed that the cell number is only a delayed indicator of cell growth compared to the biomass, which challenges the principle structure of corresponding models. Here, we evaluate adherent cell growth phases in terms of cell number and biomass increase on the basis of detailed experimental data of three independent cultivations for Madin Darby canine kidney cells. We develop a model linking cell numbers and mean cell diameters to estimate cell volume changes during growth without the need for diameter distribution measurements. It simultaneously describes the delay between cell number and cell volume increase, cell-specific volume changes and the transition from growth to maintenance metabolism while taking different pre-culture conditions, which affect the cell diameter, into account. In addition, inspection of metabolite uptake and release rates reveals that glucose is mainly used for generation of cellular energy and glutamine is not required for cellular maintenance. Finally, we conclude that changes in cell number, cell diameter and metabolite uptake during cultivation contribute to the understanding of the time course of intracellular metabolites during the cultivation process.