October 18-21, 2015
The biomanufacture of complex biologics continues to expand and develop with no end foreseen and in order to build on the industries rapid adoption of single use technology an ethos of what is measured and controlled in stainless steel can be, and should be transferable to plastic. The realization of this continues to be a challenge but one of the key critical parameters in cell cultivation; in-situ viable biomass is now quantifiable using single use capacitance measurement. A single-use sensor patch is fully integrated in a 5L Rocking Motion Bioreactor bag, gamma sterilized and applied to CHO DG44 and Hybridoma cell cultivations on a Sartorius BIOSTAT® RM Bioreactor. Compensating for the rocking motion, the 14 day capacitance results showed direct correlation with the exponential growth phase and correlation to total viable cell volume rather than viable cell concentration. This data was verified by off-line measurement of cell concentration by Cedex XS® and cell diameter by flow through measurement and microscopic distributions. Additionally, the soluble metabolite concentrations were measured to calculate the cell specific rates.
A theoretical value of capacitance can be calculated by the cell diameter with the equation;
Ctheor = theoretically measured capacitance [pF*m-2]
r = radius of the cell [m]
Cm = membrane capacitance [pF*m-2]
K = cell constant of the measurement setup [m-1]
N = cell count [m-3]
This theoretical capacitance measurement, in combination with oxygen uptake rate yields an understanding of the cellular metabolic state and whether the process is in fixed window of glucose/glutamine limitation. With this in mind, it is aimed to automate a fed-batch process where the addition of concentration media is controlled by a SCADA system control loop using Sartorius BioPAT® MFCS/win software and optimize the antibody productivity. Herein, the results and experiences of this work will be presented and discussed.
Dan Kopec, Stuart Tindal, Marcus Weise, Sven GroB, Henry Weichert, Thomas Schnitzler, Manfred Biselli, and Mario Becker, "Single-use capacitance measurement of cell viability" in "Single-Use Technologies: Bridging Polymer Science to Biotechnology Applications", Ekta Mahajan, Genentech, Inc., USA Gary Lye, University College London, UK Eds, ECI Symposium Series, (2015). http://dc.engconfintl.org/biopoly/46