Turbidimetry and Dielectric Spectroscopy as Process Analytical Technologies for Mammalian and Insect Cell Cultures
The production of biopharmaceuticals in cell culture involves stringent controls to ensure product safety and quality. To meet these requirements, quality by design principles must be applied during the development of cell culture processes so that quality is built into the product by understanding the manufacturing process. One key aspect is process analytical technology, in which comprehensive online monitoring is used to identify and control critical process parameters that affect critical quality attributes such as the product titer and purity. The application of industry-ready technologies such as turbidimetry and dielectric spectroscopy provides a deeper understanding of biological processes within the bioreactor and allows the physiological status of the cells to be monitored on a continuous basis. This in turn enables selective and targeted process controls to respond in an appropriate manner to process disturbances. This chapter outlines the principles of online dielectric spectroscopy and turbidimetry for the measurement of optical density as applied to mammalian and insect cells cultivated in stirred-tank bioreactors either in suspension or as adherent cells on microcarriers.
Key wordsProcess analytical technology Online process monitoring Optical density Dielectric spectroscopy Drosophila melanogaster S2 cells Vero cells Measles virus Cell cultivation
We thank the Federal Ministry of Education and Research (BMBF) for financial support (Grant No. 13FH001IX5), the Hessen State Ministry of Higher Education, Research and the Arts for financial support within the Hessen initiative for scientific and economic excellence (LOEWE Center for Insect Biotechnology and Bioresources), and Richard M. Twyman for professional editing of the manuscript.
- 1.International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (2009) ICH Q8(R2): pharmaceutical development. https://www.ich.org/fileadmin/Public_Web_Site/ICH_Products/Guidelines/Quality/Q8_R1/Step4/Q8_R2_Guideline.pdf
- 2.International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (1999) ICH Q6A: specifications: test procedures and acceptance criteria for new drug substances and new drug products: chemical substances. https://www.ich.org/fileadmin/Public_Web_Site/ICH_Products/Guidelines/Quality/Q6A/Step4/Q6Astep4.pdf
- 5.Eibl R, Eibl D, Pörtner R et al (eds) (2009) Cell and tissue reaction engineering. Principles and practice. Springer, Berlin, HeidelbergGoogle Scholar
- 9.Zitzmann J, Weidner T, Eichner G et al (2018) Dielectric spectroscopy and optical density measurement for the online monitoring and control of recombinant protein production in stably transformed Drosophila melanogaster S2 cells. Sensors (Basel) 18:3. https://doi.org/10.3390/s18030900CrossRefGoogle Scholar
- 27.Opel CF, Li J, Amanullah A (2010) Quantitative modeling of viable cell density, cell size, intracellular conductivity, and membrane capacitance in batch and fed-batch CHO processes using dielectric spectroscopy. Biotechnol Prog 26(4):1187–1199. https://doi.org/10.1002/btpr.425CrossRefPubMedGoogle Scholar
- 29.Schwan HP (1957) Electrical properties of tissue and cell suspensions, vol 5. Elsevier, Amsterdam, pp 147–209Google Scholar
- 32.Ansorge S, Esteban G, Schmid G (2007) On-line monitoring of infected Sf-9 insect cell cultures by scanning permittivity measurements and comparison with off-line biovolume measurements. Cytotechnology 55(2-3):115–124. https://doi.org/10.1007/s10616-007-9093-0CrossRefPubMedPubMedCentralGoogle Scholar
- 33.Zitzmann J, Sprick G, Weidner T et al (2017) Process optimization for recombinant protein expression in insect cells. In: Gowder SJT (ed) New insights into cell culture technology. InTech Open, LondonGoogle Scholar
- 37.Zeiser A, Bdard C, Voyer R et al (1999) On-line monitoring of the progress of infection in Sf-9 insect cell cultures using relative permittivity measurements. Biotechnol Bioeng 63(1):122–126. https://doi.org/10.1002/(SICI)1097-0290(19990405)63:1<122:AID-BIT13>3.0.CO;2-ICrossRefPubMedGoogle Scholar
- 38.Ansorge S, Esteban G, Schmid G (2010) Multifrequency permittivity measurements enable on-line monitoring of changes in intracellular conductivity due to nutrient limitations during batch cultivations of CHO cells. Biotechnol Prog 26(1):272–283. https://doi.org/10.1002/btpr.347CrossRefPubMedGoogle Scholar
- 46.Blüml G (2007) Microcarrier cell culture technology. In: Pörtner R (ed) Animal cell biotechnology, Methods in biotechnology. Humana Press, Totowa, NJGoogle Scholar