NTS influence on transgene expression from mono- and bicistronic plasmid vectors after lipofection in a human fibroblast cell line.
We evaluated the survival, transgene production, and copy numbers of integrated plasmid units per host genome after lipofection with mono- and bicistronic plasmid vectors in different cell lines and under various conditions. The addition of an integration enhancing murine sequence nontranscribed spacer (NTS) to the plasmids increased transfection efficiency, survival, and transgene expression. However, in human fibroblast cells this sequence had only marginal effects on overall plasmid copy number in bulk cultures. Clones producing the highest amounts of the transgene contained only one or two copies of plasmid per genome, independent of cell type and plasmid design.