Cytotechnology

, Volume 62, Issue 2, pp 121–132

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

Original Research

DOI: 10.1007/s10616-010-9267-z

Cite this article as:
Ansorge, S., Esteban, G. & Schmid, G. Cytotechnology (2010) 62: 121. doi:10.1007/s10616-010-9267-z

Abstract

Changes in the nutrient availability of mammalian cell cultures are reflected in the β-dispersion parameter characteristic frequency (fC) 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 fC occurred when feed additions were conducted. A constant or declining permittivity value in combination with a decrease in fC indicated nutrient limitations. fC correlated well with changes in oxygen uptake rate when cell diameter remained constant, indicating that metabolic activity is reflected in the value of fC. 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.

Keywords

PermittivityPhysiological stateFed-batchCHO cell cultureCharacteristic frequency

Abbreviations

BMS/Fogale BMS

Fogale Biomass System®

CASY

CASY® 1 system

CM

Capacitance per membrane area (F m−2)

ΔεFogale

(online dual-frequency) permittivity signal; difference in permittivity measured at f1 and f2

Δεmax

Permittivity increment (difference in permittivity at very low and very high frequency relative to fC)

Δεmax*fC

Mathematical product of Δεmax and fC

eq.

Equation

fC

Characteristic frequency

fig.

Figure

hema

Hemacytometer

N

Cell density

P

Volume fraction of cells (biovolume)

pHi

Intracellular pH

r

Cell radius

VC

Beckman Coulter Vi-CELL XR™ system

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.F. Hoffmann-La Roche AGBaselSwitzerland
  2. 2.FOGALE NanotechNîmesFrance
  3. 3.Biotechnology Research InstituteNational Research Council Canada, Animal Cell Technology GroupMontrealCanada