Structural Features of Totally Designed Lipidic Materials for Small Interfering RNA Delivery System

Abstract

RNA interference with small interfering RNA (siRNA) has been revealed as a powerful technique that is capable of suppressing targeted genes with high specificity. A delivery system for siRNA into mammalian cells has broadened the scope of medical intervention since siRNA has recently emerged as potential therapeutic agents in the treatment of human genetic and nongenetic diseases. Although, viral vectors are accepted as the most effective tools for gene transfer into mammalian cells in vivo and in vitro, there are safety problems such as induction of immune reactions or tumorigenesis. Therefore, the use of nonpathogenic materials based on lipids or polymers has been attempted. However, little attempt has been made to investigate how the structural features of lipidic materials are essential for delivery function. The purpose of this study was to identify the structural features of glutamate-based lipidic materials as potential siRNA carriers for intracellular delivery. Totally designed lipidic material didodecylacetylglutamatetrimethylammonium (TMA-C2-Glu-C12) and its analogs were synthesized and estimated by silencing effects of fluorescent protein (EGFP) expression in CHO cells. Here, we demonstrate that TMA-C2-Glu-C12 among a series of lipidic materials is able to perform efficient siRNA delivery with low cytotoxicity into the cells; the transfer ability resulted in 92.2% ± 1.16% of the transferred cells with Cy3-labeled siRNA. The chemical structure of TMA-C2-Glu-C12 having both hydrophobic chain (-CH2CO-) in head region, hydrophobic chain (-(CH2)11CH3) in tail regions, and ethylene (-CH2CH2-) in connector region played a crucial role to enhance the siRNA transfer efficiency. These results may improve the novel design and development of lipidic materials on siRNA delivery system.