Pre-exposure of Cells to Cationic Lipids Enhances Transgene Delivery and Expression in a Tissue Culture Cell Line

Abstract

Several factors influence non-viral transfection in tissue culture models including nature of the cationic lipid, plasmid construction, and DNA-lipid complex, amongothers. Thecell line itself is another confounding variable. Each subcellular population may respond independently to the transgene or specific delivery vector with regards to toxicity or trans-gene expression. In this study, the SKnSH (human neuroblastoma) and COS-1 (African green kidney) cells were exposed to three different treatments A, B, and C. Treatment A refers to cells obtained from American Type Culture Collection (ATCC) and cultivated as recommended, treatment B to cells that were grown in presence of cationic lipids for two weeks, and treatment C to cells that were grown in presence of cationic lipids for two weeks followed by normal media for two weeks to determine if lipid mediated effects were reversible. Treatment B resulted in a three-fold increase in transgene expression of a reporter gene as compared to the other treatments. This increase in transgene expression appeared not to be related to alterations in toxicity. Interestingly, the fluid phase endocytic uptake of fluorescently labeled oligonucleotides was increased in treatment B. However, there was no significant difference in the cellular-associated signal when fluorescently labeled plasmid-DNA was evaluated. In COS-1 cells, no difference in transfection was observed with treatment B illustrating that cell lines respond independently. In conclusion, pre-exposure of SKnSH cells to cationic liposomes (treatment B) resulted in higher transgene production.