On‐line characterization of a hybridoma cell culture process

Abstract

The on-line determination of the physiological state of a cell culture process requires reliable on-line measurements of various parameters and calculations of specific rates from these measurements. The cell concentration of a hybridoma culture was estimated on-line by measuring optical density (OD) with a laser turbidity probe. The oxygen uptake rate (OUR) was determined by monitoring dynamically dissolved oxygen concentration profiles and closing oxygen balances in the culture. The base addition for neutralizing lactate produced by cells was also monitored on-line via a balance. Using OD and OUR measurements, the specific growth and specific oxygen consumption rates were determined on-line. By combining predetermined stoichiometric relationships among oxygen and glucose consumption and lactate production, the specific glucose consumption and lactate production rates were also calculated on-line. Using these on-line measurements and calculations, the hybridoma culture process was characterized on-line by identifying the physiological states. They will also facilitate the implementation of nutrient feeding strategies for fed-batch and perfusion cultures. (c) 1994 John Wiley & Sons, Inc.

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

“…On-line optical sensors have been used in some cases to maintain the process (Merten et al 1987;Konstaninov et al 1992;Zho and Hu 1994;Wu et al 1995). In general, probe performance is acceptable for high viability culture but the light based probes do not distinguish between the viable and non-viable cells and these will also detect debris that can collect during the process.…”

“…Merten et al (1987) described an infra red sensor for determination of the cell number during continuous hybridoma fermentations but the range of cell densities tested and length of operation was limited. Laser turbidity probes have been used in batch culture (Konstantinov et al 1992;Zho and Hu 1994;Wu et al 1995) and the probe performance in general is acceptable for high viability cultures. The light based probes measure the total number of cells and during process operation upsets the optical measurements have been shown to deviate from the cell density determined by trypan blue exclusion (Wu et al 1995).…”

On-line measurement of oxygen uptake in cell culture using the dynamic method

“…Several researchers (Boraston et al, 1982;Fleischaker and Sinsky, 1981;Zhou and Hu, 1994) have used the dynamic method for determining oxygen uptake in cell culture systems. In this technique, oxygen supply is briefly interrupted and the drop in dissolved oxygen (DO) is recorded.…”

Specific heat flow rate: An on-line monitor and potential control variable of specific metabolic rate in animal cell culture that combines microcalorimetry with dielectric spectroscopy

“…While there are several off-line assays for biomass, the most basic (and time-consuming) being dry weight, it would be preferable to take advantage of the potential of heat flow rate measurements in real time by estimating biomass on-line. There are two comparable methods for this, optical density using laser light (Wu et al, 1995;Zhou and Hu, 1994) and dielectric spectroscopy (Harris et al, 1987). Because cell metabolism depends on viable biomass and in a declining metabolic condition the viability could reduce quickly, a direct measurement of viable cell mass would be ideal.…”