SAINT-liposome-polycation particles, a new carrier for improved delivery of siRNAs to inflamed endothelial cells

• Design of new SAINT-C18 and protamine based carriers for siRNA delivery.
• High siRNA encapsulation and low cellular toxicity.
• Stability and siRNA integrity comply with requirements for in vivo application.
• Efficient siRNA mediated gene downregulation in activated endothelial cells.

Interference with acute and chronic inflammatory processes by means of delivery of siRNAs into microvascular endothelial cells at a site of inflammation demands specific, non-toxic and effective siRNA delivery system. In the current work we describe the design and characterization of siRNA carriers based on cationic pyridinium-derived lipid 1-methyl-4-(cis-9-dioleyl)methyl-pyridinium-chloride) (SAINT-C18) and the transfection enhancer protamine, complexed with siRNA/carrier DNA or siRNA only. These carriers, called SAINT-liposome-polycation-DNA (S-LPD) and SAINT-liposome-polycation (S-LP), have a high efficiency of siRNA encapsulation, low cellular toxicity, and superior efficacy of gene downregulation in endothelial cells in vitro as compared to DOTAP-LPD. Incorporation of 10 mol% PEG and anti-E-selectin antibody in these formulations resulted in selective siRNA delivery into activated endothelial cells. Furthermore, we showed that the physicochemical characteristics of S-LPD and S-LP, including size-stability and maintenance of the siRNA integrity in the presence of serum at 37 °C, comply with requirements for in vivo application.

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