An Amphiphilic Dendrimer for Effective Delivery of Small Interfering RNA and Gene Silencing In Vitro and In Vivo
An Amphiphilic Dendrimer for Effective Delivery of Small Interfering RNA and Gene Silencing In Vitro and In Vivo
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DOI：
10.1002/anie.201203920
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Peng, Ling
中科院分区：
文献类型：
--
作者：
Yu, Tianzhu;Liu, Xiaoxuan;Peng, Ling
The potent ability of small interfering RNA (siRNA) to specifically and efficiently inhibit the expression of complementary RNA transcripts offers a promising alternative therapeutic approach for various diseases.[1] However, the major challenge facing siRNA-based therapy is the requirement of a safe and efficient delivery system for the siRNA.[2] Although viral vectors are highly efficient, their potential inflammatory, immunogenic, and mutagenic effects make them a safety risk and underline the urgent need for nonviral alternatives. Cationic lipids and polymers are the most common nonviral vectors: both are able to assemble the siRNA, through electrostatic interaction, into stable complexes, which can protect the siRNA from degradation and promote cell uptake.[3–5] But inadequate release of siRNA into the cytosol often constitutes one of the main obstacles for efficient nonviral delivery. Lipid vectors are presumed to achieve endosome release of siRNA through a membrane fusion mechanism,[3, 4] whereas polymeric vectors commonly use the proton sponge effect [6] to facilitate endosome escape.[5] However, lipid vectors have the drawback of being highly toxic for invivo applications and polymer delivery systems are plagued with undefined structural composition. An ideal nonviral vector would be one that is able to harness the advantageous features of both lipid and polymer vectors, while at the same time overcome or reduce their limitations. Cationic dendrimers, a special family of polymers with well-defined molecular architecture, precisely controlled chemical structure, and unique multivalent properties, are emerging as promising nonviral vectors for siRNA delivery.[7, 8] We have recently demonstrated that high generations of structurally flexible triethanolamine (TEA) core poly (-amidoamine) PAMAM dendrimers [9, 10] are effective vectors for siRNA delivery [11] in various disease models.[12–15] Here we disclose that a small amphiphilic dendrimer acts as an efficient vector to deliver siRNA in a prostate cancer model and achieve potent gene silencing and anticancer activity in vitro and in vivo. This dendrimer, a kind of lipid/dendrimer hybrid bearing a hydrophobic long alkyl chain and a lowgeneration hydrophilic PAMAM dendron, displays the advantageous delivery features of both lipid and polymer vectors. To our knowledge, this is the first report of an amphiphilic dendrimer able to successfully deliver siRNA and produce a potent gene-silencing effect in vitro and in vivo. It may constitute a promising nonviral system for siRNA delivery in future applications of therapeutic RNAs. The motivation behind us developing amphiphilic PAMAM vectors for siRNA delivery is based on the reasoning that an improved and safer delivery may be achieved by combining the special features of lipid and dendrimer vectors. We thus designed amphiphilic PAMAM dendrimers 1–3 (Scheme1) bearing different alkyl chain length and dendron size as hybrid lipid/dendrimer vectors to retain and exploit the properties of both lipid and dendrimer vectors. These dendrimers were synthesized readily using click chemistry (see Scheme S1 in the Supporting Information), and their ability to deliver siRNA and induce gene silencing was first screened on the basis of luciferase gene silencing in A549Luc cells which stably express the GL3 luciferase gene. Among the amphiphilic dendrimers 1–3, 1a allowed an exceptionally powerful gene silencing with the specific GL3Luc siRNA in serum-free medium, whereas no gene silencing was observed using the nonspecific GL2Luc siRNA bearing three mismatches (Figure 1A). The observed excellent siRNA delivery capacity of 1a was further …
