KNOWLEDGEBASE

FILTER BY SECTOR

  • On-line Measurements and Control of Viable Cell Density in Cell Culture Manufacturing Processes using Radio-frequency Impedance

    Author: John P. Carvell, Jason E. Dowd
    Publication date: 01-03-2006
    Abstract
    In this work, radio-frequency (RF) impedance is reviewed as a method for monitoring and controlling cell culture manufacturing processes. It is clear from the many publications cited that RF Impedance is regarded as an accurate and reliable method for measuring the live cell bio-volume both on-line and off-line and the technology is also suitable for animal cells in suspension, attached to micro-carriers or immobilized in fixed beds. In cGMP production, RF Impedance is being used in three main areas. Firstly, it is being used as a control instrument for maintaining consistent perfusion culture allowing the bioreactor to operate under optimum conditions for maximum production of recombinant proteins. In the second application it has not replaced traditional off-line live cell counting techniques but it is being used as an additional monitoring tool to check product conformance. Finally, RF Impedance is being used to monitor the concentration of live cells immobilized on micro-carriers or packed beds in cGMP processes where traditional off-line live cell counting methods are inaccurate or impossible to perform.
    Publication link
  • The changing dielectric properties of CHO cells can be used to determine early apoptotic events in a bioprocess.

    Author: Katrin Braasch, Et al.
    Publication date: 01/01/70
    Abstract
    Cell density and viability are two important parameters that are monitored during a mammalian cell bioprocess. The predominant method used to determine the viability of a cell population is trypan blue exclusion. This marks the loss of viability by the inability of cells to exclude the dye as a result of membrane damage. However, the loss in cell membrane integrity can be regarded as a late-stage event in the demise of cells and often indicates the end of apoptosis. Early indicators of apoptosis are desirable in cell bioprocesses because the initial stages are reversible by appropriate intervention such as nutrient feeding. In our study five different and independent methods were compared for the determination of viable and/or total cell density as well as cell viability. These included the particle counter (Coulter Counter), image analyser (Cedex with trypan blue exclusion), an on-line capacitance probe (Aber-Instruments), an off-line flow cytometer (Guava Millipore) and a prototype dielectrophoretic (DEP) cytometer. The multiple techniques of cell monitoring were applied to the culture of a novel CHO cell line producing a human-camelid chimeric antibody (EG2) grown in a bench-top bioreactor. This is a unique study which determined the relationship between these techniques and may be applied to elucidate some important properties of cells during metabolic changes in a bioprocess.
    View publication
  • The Development of large scale continuous perfusion culture system for ES Cell expansion and cardiac differentiation

    Author: Masanori Wada, Et al.
    Publication date: 28-04-2012
    Abstract
    We have recently developed scalable expansion culture and differentiation system for mouse ES cells. This system allows to : - Produce mouse cardiomyocytes by continuous and industrial scale - Eliminate labor-intensive procedure of medium exchange and differentiation by using perfusion culture system - Show the usefulness of biomass monitor for process monitoring of ES cell culture
    View publication
  • New Applications and Methods Utilizing Radio-Frequency Impedance Measurements for Improving Yeast Management

    Author:
    Publication date: 01/01/70
    Abstract
    Radio-frequency (RF) impedance or capacitance measurements are used in many of the larger automated breweries for measuring viable yeast cell concentration. This paper reports the latest applications for this technique in the yeast pitching and yeast recovery lines and new on-line methods for monitoring live yeast cell concentrations during fermentation. The new methods include a range of probes that can be inserted into either a production propagator under highly aerated conditions or a production fermenter or it can be submerged into a vessel to monitor the yeast-concentration profile in real time. The paper also describes how the RF impedance measurement can be combined with a bulk fluorescence measurement to measure both live and dead yeast cell counts.
    Publication link
  • The permittistat: a novel type of turbidostat

    Author: Gerard H. Markx, Christopher L. Davey and Douglas B. Kell
    Publication date: 01-04-1991
    Abstract
    Baker’s yeast was grown in a novel type of turbidostat in which the steady-state biomass level was controlled not by the optical turbidity but by the dielectric permittivity of the suspension at appropriate radio frequencies. Dry weight, fresh weight, the optical density at 600 nm, percentage viability (from methylene blue staining), bud count and ethanol concentration were measured off-line and the cell size distribution was recorded using flow cytometry. Any changes in the physiological properties of the yeast had a negligible effect on the ratio between the permittivity set (and measured) and the steady-state dry weight, fresh weight or optical density of the cultures. The permittistat was found to provide an extremely convenient means for carrying out turbidostatic culture.
    Publication link
< previous1 2 3 4
Page 1 of 4 (19 results)