Wolfrum, C. et al. Mechanisms and optimization of in vivo delivery of lipophilic siRNAs. Nature Biotech. 25, 1149-1157

Institute of Molecular Systems Biology, Swiss Federal Institute of Technology, ETH Zürich, HPT E73.
Nature Biotechnology (Impact Factor: 41.51). 11/2007; 25(10):1149-57. DOI: 10.1038/nbt1339
Source: PubMed


Cholesterol-conjugated siRNAs can silence gene expression in vivo. Here we synthesize a variety of lipophilic siRNAs and use them to elucidate the requirements for siRNA delivery in vivo. We show that conjugation to bile acids and long-chain fatty acids, in addition to cholesterol, mediates siRNA uptake into cells and gene silencing in vivo. Efficient and selective uptake of these siRNA conjugates depends on interactions with lipoprotein particles, lipoprotein receptors and transmembrane proteins. High-density lipoprotein (HDL) directs siRNA delivery into liver, gut, kidney and steroidogenic organs, whereas low-density lipoprotein (LDL) targets siRNA primarily to the liver. LDL-receptor expression is essential for siRNA delivery by LDL particles, and SR-BI receptor expression is required for uptake of HDL-bound siRNAs. Cellular uptake also requires the mammalian homolog of the Caenorhabditis elegans transmembrane protein Sid1. Our results demonstrate that conjugation to lipophilic molecules enables effective siRNA uptake through a common mechanism that can be exploited to optimize therapeutic siRNA delivery.

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    • "Currently, the main treatment strategies are listed as follows: (1) necessary means should be taken to enhance expression of certain miRNA, which are known to be down-regulated during the disease state. miRNA simulative technology could be adopted, that is, the mimic double-stranded RNA can be synthesized based on the endogenous miRNA sequence, and then introduced into the body to maintain the miRNA level (Wolfrum et al. 2007); (2) knocking out or silencing the target miRNA which are known to be overexpressed in the pathological process . One way to do so is to use a target miRNA complementary antisense oligonucleotide chain, whose 3' end is coupled with a cholesterol molecule to improve its inhibition effect; alternatively , one could use the miRNA sponge technology to introduce many repeated copy and incomplete complementary oligonucleotide chain by the slow virus carrier into the body (van Rooij et al. 2008). "
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