Grayson Amy C Richards, Doody Anne M, Putnam David
Department of Biomedical Engineering, The School of Chemical and Biomolecular Engineering, 270 Olin Hall, Cornell University, Ithaca, New York 14853, USA.
Pharm Res. 2006 Aug;23(8):1868-76. doi: 10.1007/s11095-006-9009-2.
The goals of this study were as follows: 1) to evaluate the efficacy of different polyethylenimine (PEI) structures for siRNA delivery in a model system, and 2) to determine the biophysical and structural characteristics of PEI that relate to siRNA delivery.
Biophysical characterization (effective diameter and zeta potential), cytotoxicities, relative binding affinities and in vitro transfection efficiencies were determined using nano-complexes formed from PEI's of 800, 25,000, (both branched) and 22,000 (linear) molecular weights at varying N:P ratios and siRNA concentrations. The HR5-CL11 cell line stably expressing luciferase was used as a model system in vitro.
Successful siRNA delivery was observed within a very narrow window of conditions, and only with the 25,000 branched PEI at an N:P ratio of 6:1 and 8:1 and with 200 nM siRNA. While the zeta potential and size of PEI:siRNA complexes correlated to transfection efficacy in some cases, complex stability may also affect transfection efficacy.
The ability of PEI to transfer functionally active siRNA to cells in culture is surprisingly dependent on its biophysical and structural characteristics when compared to its relative success and ease of use for DNA delivery.
本研究的目标如下：1）在模型系统中评估不同聚乙烯亚胺（PEI）结构用于小干扰RNA（siRNA）递送的效果，以及2）确定与siRNA递送相关的PEI的生物物理和结构特征。
使用由分子量为800、25000（均为支链型）和22000（线性）的PEI在不同的氮磷比和siRNA浓度下形成的纳米复合物，测定其生物物理特性（有效直径和zeta电位）、细胞毒性、相对结合亲和力和体外转染效率。稳定表达荧光素酶的HR5-CL11细胞系用作体外模型系统。
仅在非常狭窄的条件范围内观察到成功的siRNA递送，且仅在氮磷比为6:1和8:1以及200 nM siRNA时使用25000支链型PEI才观察到。虽然在某些情况下，PEI:siRNA复合物的zeta电位和大小与转染效率相关，但复合物稳定性也可能影响转染效率。
与PEI在DNA递送方面相对成功且易于使用相比，其将功能活性siRNA转染至培养细胞的能力令人惊讶地取决于其生物物理和结构特征。
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