Artificial selection of high proliferating and apoptosis-resistant NS0 cells for industrial production systems
It has been shown that the direct modification of metabolic networks by means of gene transfection or, genetic engineering, can cause unnecessary stresses and the metabolic overloading of cells. As a consequence, negative effects such as a reduced proliferation rate and decrease in productivity can arise; it would be more desirable to select for these factors using a directional or artificial selection approach- which can be simply achieved by altering the phenotypic mean in a population. Several specific procedures have been developed to create cell lines with improved characteristics for mammalian cell production culture systems. Primarily, natural variants with higher growth rates and apoptosis-resistance attributes were isolated using; a limiting dilution procedure, cultivating clones from prolonged batch or, culturing cells that survived a 'death-inducing' environment. The selected variants were shown to be superior in their survival, growth and productivity characteristics as compared to the parental cells and other transfected 'anti-apoptotic'/high producing variants. Stability was also maintained for prolonged periods of cultivation. This suggests the existence of natural variations in the NS0 cell line and that growth and apoptosis are selectable traits. Significant differences, as well as a negative relationship, for growth, apoptosis-resistance and productivity were identified- suggesting a fine balance exists between the advantageous use of transfection technology and any consequent effect(s) that it may cause.