Modeling suppression of cell death by Bcl-2 over-expression in myeloma NS0 6A1 cells

Abstract

A novel population-balance model was employed to evaluate the suppression of cell death in myeloma NS0 6A1 cells metabolically engineered to over-express the apoptotic suppressor Bcl-2. The model is robust in its ability to simulate cell population dynamics in batch suspension culture and in response to thymidine-induced growth inhibition: 89% of simulated cell concentrations are within two standard deviations of experimental data. Kinetic rate constants in model equations suggest that Bcl-2 over-expression extends culture longevity from 6 days to at least 15 days by suppressing the specific rate of early apoptotic cell formation by more than 6-fold and necrotic cell formation by at least 3-fold, despite nearly a 3-fold decrease in initial cell growth rate and no significant change in the specific rate of late apoptotic cell formation. This computational analysis supports a mechanism in which Bcl-2 is a common mediator of early apoptotic and necrotic events occurring at rates that are dependent on cellular factors accumulating over time. The model has current application to the rational design of cell cultures through metabolic engineering for the industrial production of biopharmaceuticals.

Development and Production of Commercial Therapeutic Monoclonal Antibodies in Mammalian Cell Expression Systems: An Overview of the Current Upstream Technologies

“…Since the apoptotic pathway is highly complex and involves many activator as well as repressor proteins, multiple targets with the aim to reduce cell death have been evaluated. Mutants that contain additional copies of genes coding for resistance to apoptosis have been constructed for both NS0 and CHO cell lines, while other approaches have relied on the use of inhibitors of apoptosis [120][121][122][123][124][125][126][127]. Overall increases in longevity have been observed and some correlations with increased mAb secretion have been observed.…”