Department of Pharmaceutical Sciences, University of Modena & Reggio Emilia, Via Campi, 41100 Modena, Italy.
Nanomedicine (Lond). 2011 Apr;6(3):423-36. doi: 10.2217/nnm.11.11.
Nanoneuroscience, based on the use polymeric nanoparticles (NPs), represents an emerging field of research for achieving an effective therapy for neurodegenerative diseases. In particular, poly-lactide-co-glycolide (PLGA) glyco-heptapetide-conjugated NPs (g7-NPs) were shown to be able to cross the blood-brain barrier (BBB). However, the in vivo mechanisms of the BBB crossing of this kind of NP has not been investigated until now. This article aimed to develop a deep understanding of the mechanism of BBB crossing of the modified NPs.
MATERIALS & METHODS: Loperamide and rhodamine-123 (model drugs unable to cross the BBB) were loaded into NPs, composed of a mixture of PLGA, differently modified with g7 or with a random sequence of the same aminoamids (random-g7). To study brain targeting of these model drugs, loaded NPs were administered via the tail vein in rats in order to perform both pharmacological studies and biodistribution analysis along with fluorescent, confocal and electron microscopy analysis, in order to achieve the NP BBB crossing mechanism. Computational analysis on the conformation of the g7- and random-g7-NPs of the NP surface was also developed.
Only loperamide delivered to the brain with g7-NPs created a high central analgesia, corresponding to the 14% of the injected dose, and data were confirmed by biodistribution studies. Electron photomicrographs showed the ability of g7-NPs in crossing the BBB as evidenced by several endocytotic vesicles and macropinocytotic processes. The computational analysis on g7 and random-g7 showed a different conformation (linear vs globular), thus suggesting a different interaction with the BBB.
Taken together, this evidence suggested that g7-NP BBB crossing is enabled by multiple pathways, mainly membrane-membrane interaction and macropinocytosis-like mechanisms. The results of the computational analysis showed the Biousian structure of the g7 peptide, in contrast to random-g7 peptide (globular conformation), suggesting that this difference is pivotal in explaining the BBB crossing and allowing us to hypothesize regarding the mechanism of BBB crossing by g7-NPs.
基于聚合物纳米粒子（NPs）的纳米神经科学代表了一种新兴的研究领域，旨在实现神经退行性疾病的有效治疗。特别是聚丙交酯-乙交酯（PLGA）糖七肽偶联纳米粒子（g7-NPs）已被证明能够穿过血脑屏障（BBB）。然而，直到现在，还没有人研究过这种 NP 通过 BBB 的体内机制。本文旨在深入了解修饰后的 NPs 通过 BBB 的机制。
将洛哌丁胺和罗丹明 123（无法穿过 BBB 的模型药物）装载到由 PLGA 组成的 NPs 中，该 NPs 经过不同的修饰，分别与 g7 或相同氨基酸的随机序列（随机-g7）偶联。为了研究这些模型药物的脑靶向性，通过尾静脉给予载药 NP，进行药理学研究和生物分布分析，同时进行荧光、共聚焦和电子显微镜分析，以确定 NP 通过 BBB 的机制。还对 NP 表面 g7-NP 和随机-g7-NP 的构象进行了计算分析。
只有用 g7-NP 递送到大脑的洛哌丁胺才会产生高中枢镇痛作用，相当于注射剂量的 14%，并且通过生物分布研究得到了证实。电子显微镜照片显示 g7-NP 具有穿过 BBB 的能力，证据是有多个内吞小泡和巨胞饮过程。g7 和随机-g7 的计算分析显示出不同的构象（线性与球形），因此表明与 BBB 的不同相互作用。
综上所述，这些证据表明 g7-NP 通过 BBB 的穿越是通过多种途径实现的，主要是膜-膜相互作用和巨胞饮样机制。计算分析的结果显示 g7 肽具有 Biousian 结构，而随机-g7 肽则具有球形构象（globular conformation），这表明这种差异对于解释 BBB 穿越至关重要，并使我们能够假设 g7-NP 通过 BBB 的机制。
