Structure, activity and uptake mechanism of siRNA-lipid nanoparticles with an asymmetric ionizable lipid.
Lipid nanoparticles (LNPs) represent the most advanced platform for the systemic delivery of siRNA. We have previously reported the discovery of novel ionizable lipids with asymmetric lipid tails, enabling potent gene-silencing activity in hepatocytes in vivo; however, the structure and delivery mechanism had not been elucidated. Here, we report the structure, activity and uptake mechanism of LNPs with an asymmetric ionizable lipid. Zeta potential and hemolytic activity of LNPs showed that LNPs were neutral at the pH of the blood compartment but become increasingly charged and fusogenic in the acidic endosomal compartment. (31)P NMR experiments indicated that the siRNA was less mobile inside particles, presumably because of an electrostatic interaction with an ionizable lipid. The role of Apolipoprotein E (apoE) was studied using recombinant human apoE both in vitro and in vivo. A comparative study in wild-type and apoE-deficient mice revealed that apoE significantly influenced the in vivo biodistribution of LNPs and enhanced the cellular uptake. Pretreatment of mice with siRNA targeting low-density lipoprotein receptor (LDLR) impaired gene-silencing of the following siRNA treatment, demonstrating that in vivo activity of LNPs is dependent on LDLR. Our studies on the detailed mechanism should lead to the creation of more sophisticated LNP-based RNAi therapeutics.
['Suzuki|Yuta|Y|', 'Ishihara|Hiroshi|H|']
D000818:Animals D004305:Dose-Response Relationship, Drug D005260:Female D006367:HeLa Cells D006801:Humans D008055:Lipids D051379:Mice D008807:Mice, Inbred BALB C D008813:Mice, Inbred ICR D053758:Nanoparticles D034741:RNA, Small Interfering D011994:Recombinant Proteins D013329:Structure-Activity Relationship D014018:Tissue Distribution
Lipid nanoparticles siRNA Drug delivery Gene silencing Nanomedicines