19F MRS assessment of siRNA delivery to vascular cells via perfluorocarbon nanoparticles
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KeywordsImaging Agent 2F2B Cell Cationic Lipid Lipid Monolayer Delivery Agent
RNA interference mediated by the introduction of exogenous siRNAs has been a powerful tool for the modulation of gene expression. The ability to track siRNA delivery would be advantageous for future in vivo studies.
To design a synthetic vehicle to serve as both an siRNA delivery agent and an imaging agent, perfluorocarbon nanoparticles (PFC-NP) were loaded with the cationic lipid 1, 2-Dioleoyl-3-Trimethylammonium-Propane (DOTAP) in the lipid monolayer to form transfection complexes with siRNA to the VCAM-1 gene. siRNA loading onto nanoparticles was measured via PAGE gel. Mouse 2F2B endothelial cells were incubated with transfection complexes (PFC-NP/siRNA) for 4 h. 19F MR spectroscopy was performed at 11.7 T to determine the number of NP bound to each cell. mRNA levels were measured 48 h after transfection to determine knockdown.
The loading conditions used in this experiment resulted in 645 siRNA molecules per nanoparticle. Incubation with 2F2B cells led to a roughly linear increase in bound nanoparticles over the range of concentrations tested. In one condition which resulted in a 72% reduction in VCAM-1 mRNA levels, 19F spectroscopy data reported 5563 particles per cell.
For future in vivo studies, a trackable delivery agent would aid in the determination of localization of siRNA delivery to specific tissues. To this end, we have developed a nanoparticle which is able to deliver siRNA to mouse endothelial cells and whose signal can be detected by 19F MR spectroscopy and imaging.
This article is published under license to BioMed Central Ltd.