(638b) Endocytosis Controls siRNA Efficiency and Cell Specific Targeting

Understanding the relationship between delivery vehicle characteristics and the endocytosis and intracellular trafficking of short interfering RNAs (siRNAs) remains a critical bottleneck in the development of siRNA therapeutics. Poor delivery vehicle design can result in inefficient delivery, cytotoxicity, or immunogenicity when used in vivo. Emerging information about endocytic pathways has revealed the pathway of endocytosis influences both the composition of endosomal membranes and subsequent routes of intracellular trafficking. Given these findings, we explored the role of endocytosis in the active delivery of siRNAs (whether by Clathrin, Caveolin, Arf6, Graf1, Flotillin, or Macropinocytosis) across multiple cell types (HeLa (cervical), H1299 (lung), HEK293 (kidney), and HepG2 (liver)). In this study, we demonstrated that the optimal pathway for internalization of siRNAs and initiation of RNAi varies by cell type and that the intracellular accumulation of siRNAs and silencing can even be enhanced by inhibition of other, sub-optimal pathways.