Monitoring CHO cell cultures: cell stress and early apoptosis assessment by mass spectrometry

Abstract

Mammalian cells, especially CHO (Chinese Hamster Ovary), are an important host for the production of biopharmaceuticals. Early detection of cellular stress and the onset of apoptosis, ultimately leading to a reduced viability of the culture, are important with respect to process development and monitoring. In this work, intact cell MALDI mass spectrometry (ICM MS) biotyping was used to rapidly and sensitively detect cell stress and the onset of apoptosis at line in CHO cell cultures. We describe the identification of specific and highly reproducible stress and apoptosis related changes in m/z signal intensities that allowed prediction of upcoming cell viability changes approximately 24h earlier than standard culture monitoring. Furthermore, early identification of apoptosis onset was comparable to that using a sensitive, albeit offline, detection method. By comparison with ICM MS analysis of apoptosis induced cultures, many of the m/z values were identified as apoptosis-specific. A classification model for discrimination of unknown samples regarding their cellular viability/apoptosis status was developed based on a condensed set of 51 m/z values. The fast, robust and automated acquisition of cell state specific MS signatures could become a promising tool for CHO culture monitoring.

Keywords: Apoptosis; Cell culture; MALDI TOF MS; Monitoring; Viability.