Real-time growth monitoring of stem cell cultures using off-gas analysis in T-flasks and spinner flasks

Off-gas analysis is a valuable tool which enables non-invasive measurement of a cell cultures metabolic activity in real-time. While specialized measurement devices, e.g., the Kuhner TOM, have been developed for use with suspension cells cultivated in shake flasks, analytical devices compatible with small-scale cultivation systems used for adherent cells are still lacking. To bridge this gap, the Kuhner TOM system was adapted for use with spinner- and T-flasks in this study, as depicted in Figure 1. Since the metabolic activity of adherent stem cell cultures is at least one order magnitude lower than what is typical for suspension cell cultures, measurement sensitivity had to be improved while external interferences had to be minimised. Proof of concept cultivations of human mesenchymal stem cells were carried out in T25-flasks and in spinner flasks (using microcarriers), showcasing that the noninvasively measured metabolic activity correlated well with the cell growth measured offline. Simultaneously, the cell specific oxygen consumption of the cultivated cells could be determined to be between 2 – 5 ∙ 10−17 mol cell−1 s−1, which agrees with literature values.