School of Pharmacy, Kitasato University, Shirokane 5-9-1, Minato-ku, Tokyo 108-8641, Japan.
School of Pharmacy, Kitasato University, Shirokane 5-9-1, Minato-ku, Tokyo 108-8641, Japan.
Biochim Biophys Acta Biomembr. 2021 Aug 1;1863(8):183627. doi: 10.1016/j.bbamem.2021.183627. Epub 2021 Apr 24.
To enable the release of the encapsulated nucleic acids into the cytosol of targeted cells, the interaction of lipid nanoparticles (LNPs) with endosomes is critical. We investigated changes in the physicochemical properties of LNPs containing ionizable cationic lipids that were induced by acidic pH, which reflects the conditions in the maturation of endosomes. We prepared a LNP containing an ionizable cationic lipid. The laurdan generalized polarization values, which are related to the hydration degree of the lipid membrane interface and are often used as an indicator of membrane packing, decreased with a decrease in pH value, showing that the membrane packing was decreased under acidic conditions. Furthermore, the pH-induced variation increased with an increasing percentage of ionizable cationic lipids in the LNPs. These results indicated that electrostatic repulsion between lipid molecules at acidic pH decreased the packing density of the lipids in the LNP membrane. Reducing the order of lipids could be a trigger to form a non-bilayer structure and allow fusion of the LNPs with the membrane of maturing endosomes in an acidic environment. The LNPs were used to incorporate and transport small interfering RNA (siRNA) into cells for knockdown of the expression of β-galactosidase. The knockdown efficiency of siRNA encapsulated in LNPs tended to increase with the ratio of KC2. These results, which demonstrate the underlying phenomena for the fusion of membranes, will help clarify the mechanism of the release of encapsulated nucleic acids.
为了使包裹的核酸释放到靶细胞的细胞质中，脂质纳米颗粒（LNPs）与内体的相互作用至关重要。我们研究了带正电的可离子化脂质的 LNPs 的物理化学性质在酸性 pH 下的变化，酸性 pH 反映了内体成熟过程中的条件。我们制备了一种含有可离子化阳离子脂质的 LNPs。Laurdan 普遍极化值与脂质膜界面的水合程度有关，常用于指示膜包装，随着 pH 值的降低而降低，表明在酸性条件下膜包装减少。此外，pH 诱导的变化随着 LNPs 中可离子化阳离子脂质的百分比增加而增加。这些结果表明，酸性 pH 下脂质分子之间的静电排斥降低了 LNPs 膜中脂质的堆积密度。减少脂质的有序性可能是形成非双层结构的触发因素，并允许 LNPs 在酸性环境下与成熟内体的膜融合。LNPs 用于将小干扰 RNA（siRNA）包裹并转运到细胞中，以降低β-半乳糖苷酶的表达。包裹在 LNPs 中的 siRNA 的敲低效率随着 KC2 比例的增加而增加。这些证明膜融合潜在现象的结果将有助于阐明包裹核酸释放的机制。
