MALDI-TOF mass spectrometry biotyping: At line monitoring of recombinant CHO cell cultures

Background The cultivation of mammalian cells, especially Chinese Hamster Ovary (CHO), has found widespread acceptance for the production of biopharmaceuticals. Process monitoring enforced by the PAT initiative of the FDA underwent major changes from examining the bioreactor/culture as a “black-box” towards integrated methods, helping to gain deeper process understanding by assessing the cells themselves. Previously, we presented first results of CHO batch cultures assessed in order to monitor cell stress and early apoptosis by Intact Cell MALDI-TOF Mass Spectrometry (ICM MS) biotyping, a method originally used in clinical microbiology [1]. Now, we broadened its application and addressed additional CHO cell lines (DXB11 and CHOK1), different cultivation-formats (uncontrolled Erlenmeyer flasks vs. lab scale bioreactors) and operation modes (Batch vs. Perfusion). Furthermore, we transferred the method to a compact, “low-priced” mass spectrometer (MicroFlex, Bruker Daltonik, Bremen, Germany). The experimental aim was to establish characteristic MS patterns indicative for different apoptotic states with emphasis on detection of early apoptosis ubiquitously applicable independent of CHOsubline, cultivation-format, -mode or instrumental equipment (MS).