Verhulst and stochastic models for comparing mechanisms of MAb productivity in six CHO cell lines

Mechanochemical Synergism of Reactive Oxygen Species Influences on RBC Membrane

The influences of various factors on blood lead to the formation of extra reactive oxygen species (ROS), resulting in the disruption of morphology and functions of red blood cells (RBCs). This study considers the mechanisms of the mechanochemical synergism of OH• free radicals, which are most active in the initiation of lipid peroxidation (LPO) in RBC membranes, and H2O2 molecules, the largest typical diffusion path. Using kinetic models of differential equations describing CH2O2t and COH•t, we discuss two levels of mechanochemical synergism that occur simultaneously: (1) synergism that ensures the delivery of highly active free radicals OH• to RBC membranes and (2) a positive feedback system between H2O2 and OH•, resulting in the partial restoration of spent molecules. As a result of these ROS synergisms, the efficiency of LPO in RBC membranes sharply increases. In blood, the appearance of OH• free radicals is due to the interaction of H2O2 molecules with free iron ions (Fe2+) which arise as a result of heme degradation. We experimentally established the quantitative dependences of COH• CH2O2 using the methods of spectrophotometry and nonlinear curve fitting. This study extends the analysis of the influence of ROS mechanisms in RBC suspensions.

OPP Labeling Enables Total Protein Synthesis Quantification in CHO Production Cell Lines at the Single-Cell Level

Accurate measurement of global and specific protein synthesis rates is becoming increasingly important, especially in the context of biotechnological applications such as process modeling or selection of production cell clones. While quantification of total protein translation across whole cell populations is easily achieved, methods that are capable of tracking population dynamics at the single-cell level are still lacking. To address this need, we apply O-propargyl-puromycin (OPP) labeling to assess total protein synthesis in single recombinant Chinese hamster ovary (CHO) cells by flow cytometry. Thereby we demonstrate that global protein translation rates slightly increase with progression through the cell cycle during exponential growth. Stable CHO cell lines producing recombinant protein display similar levels of total protein synthesis as their parental CHO host cell line. Global protein translation does not correlate with intracellular product content of three model proteins, but the host cell line with high transient productivity has a higher OPP signal. This indicates that production cell lines with increased overall protein synthesis capacity can be identified by our method at the single-cell level. In conclusion, OPP-labeling allows rapid and reproducible assessment of global protein synthesis in single CHO cells, and can be multiplexed with DNA staining or any type of immunolabeling of specific proteins or markers for organelles.