Key Laboratory of Smart Drug Delivery, Ministry of Education & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, China.
Key Laboratory of Smart Drug Delivery, Ministry of Education & State Key Laboratory of Molecular Engineering of Polymers, School of Pharmacy, Fudan University, Shanghai 201203, China.
J Control Release. 2018 Jun 10;279:220-233. doi: 10.1016/j.jconrel.2018.04.034. Epub 2018 Apr 19.
β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a key enzyme to cleave the amyloid precursor protein to develop Alzheimer's disease (AD). Reducing BACE1 expression in central neuron through RNA interference technology shows great promise to overcome AD. However, to obtain an efficient and neurons-specific delivery of siRNA against BACE1 through systemic administration remains challenging. Here, we design and prepare siRNA nano-carriers based on PEGylated poly(2-(N,N-dimethylamino) ethyl methacrylate) (PEG-PDMAEMA) modified with both the CGN peptide for blood-brain barrier (BBB) penetration and the Tet1 peptide for neuron-specific binding. The nanocomplexes CT/siRNA, composed of CGN-PEG-PDMAEMA and Tet1-PEG-PDMAEMA at a weight ratio of 1:1, display a good stability in the blood and do not lead to hemolysis at N/P = 10. The internalization of nanocomplexes in neuron cells relies on clathrin-mediated endocytosis and micropinocytosis, while caveolae-mediated endocytosis plays a major role in entrance of CT/siRNA into cerebral capillary endothelial cell bEnd.3. The nanocomplexes successfully escape from lysosomes and enter in the cytoplasm of the neuron cells, inducing effective gene silence (about 50% decrease in BACE1 mRNA levels) and reversing Aβ oligomer-induced synaptic injury. After caudal vein injection in mice, CT/siRNA display higher brain accumulation than unmodified nanocomplexes (brain drug targeting index = 2.62), and colocalize with neurons or locate nearby. In APP/PS1 transgenic mice, the nanocomplexes significantly decrease BACE1 mRNA and the amyloid plaques, suppress phosphorylated tau protein levels, as well as promote hippocampal neurogenesis. Noticeably, administration of the nanocomplexes restores the cognitive performance of the AD transgenic mice to the level of wild-type control without significant adverse effects on myelination. Our results demonstrate the CT/siRNA nanocomplexes capable of specifically directing BACE1 siRNA to brain neurons with great potential for AD therapy.
β-淀粉样前体蛋白裂解酶 1（BACE1）是切割淀粉样前体蛋白以引发阿尔茨海默病（AD）的关键酶。通过 RNA 干扰技术降低中枢神经元中的 BACE1 表达显示出克服 AD 的巨大前景。然而，通过全身给药获得针对 BACE1 的高效和神经元特异性 siRNA 传递仍然具有挑战性。在这里，我们设计并制备了基于聚（2-（N，N-二甲基氨基）乙基甲基丙烯酸酯）（PEG-PDMAEMA）的 siRNA 纳米载体，该载体同时修饰了 CGN 肽用于血脑屏障（BBB）穿透和 Tet1 肽用于神经元特异性结合。纳米复合物 CT/siRNA 由 CGN-PEG-PDMAEMA 和 Tet1-PEG-PDMAEMA 以 1:1 的重量比组成，在血液中表现出良好的稳定性，并且在 N/P=10 时不会导致溶血。纳米复合物在神经元细胞中的内化依赖于网格蛋白介导的内吞作用和微饮作用，而 caveolae 介导的内吞作用在 CT/siRNA 进入脑毛细血管内皮细胞 bEnd.3 中起主要作用。纳米复合物成功地从溶酶体逃逸并进入神经元细胞的细胞质中，诱导有效的基因沉默（BACE1 mRNA 水平降低约 50%）并逆转 Aβ 寡聚体诱导的突触损伤。在小鼠尾静脉注射后，CT/siRNA 比未修饰的纳米复合物具有更高的脑积累（脑药物靶向指数=2.62），并与神经元共定位或位于附近。在 APP/PS1 转基因小鼠中，纳米复合物显著降低 BACE1 mRNA 和淀粉样斑块，抑制磷酸化 tau 蛋白水平，并促进海马神经发生。值得注意的是，纳米复合物的给药恢复了 AD 转基因小鼠的认知表现，使其达到野生型对照的水平，而对髓鞘形成没有明显的不良影响。我们的结果表明，CT/siRNA 纳米复合物能够特异性地将 BACE1 siRNA 递送到大脑神经元，为 AD 治疗提供了巨大的潜力。
