Department of Polymer Science and Technology, Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
Laboratory of Nucleic Acid Technology, Institute of Molecular Medicine, Peking University, Beijing 100871, China.
Biomaterials. 2015 Apr;48:45-55. doi: 10.1016/j.biomaterials.2015.01.026. Epub 2015 Feb 9.
Due to their biodegradable character, polyesters such as polycaprolactone (PCL), poly(D,L-lactide) (PDLLA), and polylactic-co-glycolic acid (PLGA) were widely used as the hydrophobic cores of amphiphilic cationic nanoparticles (NPs) for siRNA delivery. However, fewer researches focused on facilitating siRNA delivery by adjusting the polyester composition of these nanoparticles. Herein, we investigated the contribution of polyester segments in siRNA delivery in vitro by introducing different ratio of DLLA moieties in PCL segments of mPEG-block-PCL-graft-poly(dimethylamino ethyl methacrylate)(PEG-b-PCL-g-PDMAEMA). It was noticed that compared with the other ratios of DLLA moieties, a certain molar ratio (about 70%) of the NPs, named mPEG45-P(CL21-co-DLLA48)-g-(PDMAEMA29)2 (PECLD-70), showed the highest gene knockdown efficiency but poorest cellular uptake ability in vitro. Further research revealed that NPs with various compositions of the polyester cores showed different physicochemical properties including particle size, zeta potential and stiffness, leading to different endocytosis mechanisms thus influencing the cellular uptake efficiency. Subsequently, we observed that the cells treated by PECLD-70 NPs/Cy5 siRNA complexes exhibited more diffuse Cy5 signal distribution than other NPs by confocal laser scanning microscope, which suggested that siRNA delivered by PECLD-70 NPs/Cy5 siRNA complexes possessed of stronger capabilities in escaping from endosome/lysosome, entering the RNA-induced silencing complex (RISC) and cutting the target mRNA efficiently. The different siRNA release profile was dominated by the degradation rate of polyester segments. Therefore, it could be concluded that the adjustment of hydrophobic core of cationic nanoparticles could significantly affect their transfection behavior and appropriate polyester composition should be concerned in designing of analogous siRNA vectors.
由于其可生物降解的特性，聚己内酯（PCL）、聚（D，L-丙交酯）（PDLLA）和聚乳酸-共-羟基乙酸（PLGA）等聚酯被广泛用作两亲阳离子纳米粒子（NPs）的疏水核心，用于 siRNA 的递送。然而，较少的研究集中在通过调整这些纳米粒子的聚酯组成来促进 siRNA 的递送。在此，我们通过在 mPEG 嵌段-PCL-接枝-聚（二甲基氨基乙基甲基丙烯酸酯）（PEG-b-PCL-g-PDMAEMA）的 PCL 段中引入不同比例的 DLLA 部分，研究了聚酯段在体外 siRNA 递送中的贡献。结果表明，与其他 DLLA 部分的比例相比，某些摩尔比（约 70%）的 NPs，命名为 mPEG45-P（CL21-co-DLLA48）-g-（PDMAEMA29）2（PECLD-70），显示出最高的基因敲低效率，但在体外的细胞摄取能力最差。进一步的研究表明，具有不同聚酯核组成的 NPs 表现出不同的物理化学性质，包括粒径、Zeta 电位和刚性，从而导致不同的内吞机制，从而影响细胞摄取效率。随后，我们观察到，用 PECLD-70 NPs/Cy5 siRNA 复合物处理的细胞通过共聚焦激光扫描显微镜显示出比其他 NPs 更弥散的 Cy5 信号分布，这表明 PECLD-70 NPs/Cy5 siRNA 复合物递送的 siRNA 具有更强的从内涵体/溶酶体逃逸、进入 RNA 诱导沉默复合物（RISC）并有效切割靶 mRNA 的能力。不同的 siRNA 释放谱主要由聚酯段的降解速率决定。因此，可以得出结论，阳离子纳米粒子疏水核的调节可以显著影响其转染行为，在设计类似的 siRNA 载体时应考虑适当的聚酯组成。
