Real‐time in situ monitoring of freely suspended and immobilized cell cultures based on mid‐infrared spectroscopic measurements

Abstract

Glucose and lactate profiles in Chinese hamster ovary cell cultures were accurately monitored in real time and in situ during three bioreactor batch cultures lasting 11,15, and 15 days performed within a 60-day period. Monitoring was accomplished using in situ-collected mid-infrared spectra analyzed with a priori one-time established partial least-squares regression models. The robustness of the technique was demonstrated by application of these models without modification after 2.3 years. Neither recalibration nor instrument maintenance was required during the 2.3-year period, except for the daily filling of liquid nitrogen for detector cooling during operation. The lactate calibration model yielded accurate absolute concentration estimations during each of the batch cultures with standard errors of estimate from 1 to 3 mM. The a priori-established glucose calibration model yielded concentration estimations with an off-set, which was constant throughout a culture. Adjustment of the off-set before inoculation resulted in accurate concentration estimations with Standard errors of estimate of approximately 1 mM for each of the bioreactor cultures. Sensitivity in detecting differences of 0.5 mM and selectivity against variation of one metabolite while the other was kept constant was demonstrated during standard additions of either glucose or lactate. The sensor system proved to be reliable, simple, accurate, sterile, and capable of long-term automatic operation and is considered to be mature enough to be routinely applied for in situ (on-line) cell culture monitoring.

On‐line monitoring of human prostate cancer cells in a perfusion rotating wall vessel by near‐infrared spectroscopy

“…When calibration models from off-line-collected spectra are established at some time prior to the application of these models to on-line-collected spectra, instrumental variations may have occurred. In the case discussed by Rhiel et al (2002b), off-sets could be attributed to differences in instrument alignment. The observed off-sets, however, were constant throughout each complete culture.…”

“…The observed off-sets, however, were constant throughout each complete culture. Rhiel et al (2002b) showed that subtraction of the initial on-line prediction off-set resulted in accurate concentration predictions throughout the culture progression. The present situation is similar in that calibration models were established a priori with off-line-collected spectra.…”

“…4l -k) was greatly improved by adopting the methodology of initial off-set correction from Rhiel et al (2002b). The initial off-sets observed and the SEP values resulting after adjustment are summarized in Table III.…”

“…In general, a prioriestablished calibration models are useful for frequent subsequent cultivations when operator time and costs are to be minimized. For example, Rhiel et al (2002b) described the establishment of one-time calibration models, which were still valid after 2 to 3 years. The calibration models were established using randomly spiked off-line tissue culture samples.…”

Online monitoring of microcarrier based fibroblast cultivations with in situ microscopy

“…The efficiency of a bioprocess can be optimized if the growth and morphology of the microorganisms used are monitored inline continuously, that is in real time without any offline sampling (Camisard et al, 2002). There exist various direct and indirect methods for the online measurement of cell concentration which are described in the literature (Konstantinov et al, 1994;Marose et al, 1999;Rhiel et al, 2001;Sonnleitner et al, 1992).…”