聚乙烯亚胺及其衍生物介导siRNA递送的研究进展

目的介绍非病毒载体聚乙烯亚胺(PEI)及其衍生物介导小干扰RNA(siRNA)递送的研究现状,为开发新型载体开阔思路。方法查阅国内外有关文献,总结、归纳已报道的递送siRNA的各种PEI载体及其相关研究。结果与结论综述了单独PEI、各种PEI衍生物递送siRNA的研究进展。PEI等聚合物基因载体由于其设计灵活在核酸递送中显示了巨大的潜力,随着对PEI聚合物转染机制的进一步研究与结构的合理修饰,PEI及其衍生物将会在非病毒载体领域扮演更重要的角色。

In vitro comparative evaluation of three CLD/siRNA nanoplexes prepared by different processes

In this study, a gemini-like cationic lipid （CLD） was used as the carrier to study the complexation features of CLD/ siRNA nanoplexes （CLD/siRNA NPs）. Three types of CLD/siRNA nanoplexes （named as AT NPs, HT NPs and MT NPs） were prepared by different processes： AT method （mixing siRNA solution with preformed CLD nanoparticles）, HT method （hydrating a CLD thin film with siRNA solution）, and MT method （dropping an ethanolic solution of CLD into siRNA solution under sonication）. The particle size, zeta potential, morphology, siRNA protection, cytotoxicity, cellular uptake, and targeted mRNA downregulation were studied. At the optimal N/P ratio of 10, the sizes of the three CLD/siRNA NPs were MT NPs （（222.3±19.1） nm）〉 HT NPs （（105.7±1.31） nm）〉AT NPs （（91.8±1.75） nm）. Different nanostructures were formed despite the fact that they were composed of the same components. Furthermore, the TEM images indicated that different morphologies were found in the three NPs, indicating that the nanoplexes were assembled by different mechanisms. Among the three NPs, the cell uptake capacity were as follows： AT NPs〉MT NPs〉HT NPs, whereas the silencing levels on epidermal growth factor receptor （EGFR） in HeLa cells were MT NPs〉AT NPs〉HT NPs. Based on the above results, we hypothesized that the different preparation processes resulted in nanostructures with varying biological effects. Therefore, we believe that structural optimization of siRNA nanoplexes is essential in achieving better siRNA encapsulation, protection, and gene silencing efficiency.

Novel cationic lipid with reduction-responsive cleavable hydrophobic tail for siRNA delivery

To achieve a higher transfection efficiency and lower toxicity, a novel herringbone-like cationic lipid（2 ss HLL） composed of hydrophilic aspartic acid linked with two reduction-responsive cleavable hydrophobic oleic acid tails was synthesized and assessed in this study. In our results, the cationic nanoplexes with a uniform spherical shape and a particle size of ~150 nm were successfully prepared by the electrostatic interaction between si RNAs and 2 ss HLL-based liposomes. From the results evaluated in Hep G2 cells, it was shown that the nanoplexes exhibited high cellular uptake of si RNA with a low cytotoxicity. Moreover, the significant down-regulation effects of 2 ss HLL/si EGFR nanoplexes on target m RNA were displayed by RT-PCR analysis, which were similar to those of Lipofectamine2000. It suggested that the enhanced si RNA gene silencing efficiency was probably attributed to the detachment of hydrophobic tail chains induced by reduction-responsive cleavage. This mechanism was also confirmed by the changes of size distribution and si RNA release of nanoplexes in the reductive environment and DTT-absence condition. Overall, we believed that the redox-active herringbone-like 2 ss HLL would be a potential nanocarrier towards si RNA delivery.

Riboflavin-modified lipo-polyplexes co-delivering CXCR4 siRNA and doxorubicin for treatment of highly metastatic cancer

SDF-1/CXCR4 has been recognized as one of the most relevant chemokine signaling pathways to cancer metastasis,and siRNA targeting CXCR4 may provide potential improvements to treat those highly metastatic cancers,especially when combined with chemotherapy.In the present study,we constructed riboflavin-modified lipo-polyplexes to co-deliver CXCR4 siRNA and doxorubicin for cancer therapy.Doxorubicin was covalently conjugated to polyethyleneimine(PEI)with acid-cleavable hydrazine bond,and the obtained acid-sensitive conjugate was efficiently condensed with siRNA to form polyplexes,which were further coated with riboflavin-tailed lipid-membrane to prepare the lipo-polyplexes conveniently.Utilizing the fact that tumor cells overexpress riboflavin receptors,the riboflavin modification effectively enhanced uptake of lipo-polyplexes by tumor cells in a receptor-mediated manner.The riboflavin-modified lipo-polyplexes co-delivering CXCR4 siRNA and doxorubicin effectively decreased viability and invasiveness of tumor cells in vitro,and inhibited primary tumor growth and tumor metastasis in vivo.

Biomimetic gold nanocomplexes for gene knockdown： Will gold deliver dividends for small interfering RNA nanomedicines？

RNA interference （RNAi） effectors such as small interfering RNA （siRNA） and micro RNA （miRNA） can selectively downregulate any gene implicated in the pathology of a disease. Therefore, RNAi-based therapies have immense potential for the treatment of a wide range of diseases. However, pharmacokinetic and pharmacodynamic studies have revealed that these therapeutic agents have poor bioactivity due to a number of factors, including insufficient plasma drug levels, short plasma half-lives, renal clearance, and hepatic metabolism. Non-viral delivery may facilitate the clinical application of siRNA-based therapeutics by helping to overcome these barriers. Recently, the potential of gold nanoparticles （AuNPs） as multifunctional carriers for transporting drugs, proteins, and genetic materials has been demonstrated. In this review, some of the key properties of AuNPs relevant to siRNA delivery, such as physical properties and surface chemistry have been described. In addition, the ability of AuNP-based formulation strategies to successfully overcome delivery barriers associated with siRNA, and the potential for this material to translate into safe and effective nanomedicines are critically discussed.