聚乳酸纳米粒穿透血脑屏障的分析电镜研究

Polylactic Acid Nanoparticles Across the Brain-blood Barrier Observed with Analytical Electron Microscopy

观察以聚乳酸 (D ,L polylacticacid ,PLA)为材料制备、经吐温 80 (T 80 )表面改性的纳米粒对血脑屏障的穿透效果并探讨其机制 ,分别将FITC Dextran、叶绿素铜作为PLA纳米粒的示踪标记 ,应用荧光显微镜、透射电镜及分析电镜观察经静脉注射入小鼠体内的PLA纳米粒在脑组织中的分布、穿透血脑屏障的特性。荧光显微镜观察到小鼠脑组织中散在及沿毛细血管壁分布的荧光颗粒 ,透射电镜可观察到小鼠脑毛细血管内皮细胞及周围脑组织中圆形或类圆形的外源性纳米粒 ;进一步采用分析电镜对颗粒处组织进行能谱分析证实其为叶绿素铜标记的PLA纳米粒。证实了T 80修饰的PLA纳米粒具有穿透血脑屏障的特性 ,机制可能是毛细血管内皮细胞的胞吞转运作用 ,同时 。

The blood brain barrier (BBB) is a huge obstacle in therapy of brain diseases, for it hinders the delivery of water soluble molecules and those with molecular weight above 500 from the circulation system to the brain. Polysorbate 80 (Tween 80 ,T 80) coated polylactid acid(PLA) nanoparticles represent a tool to transport such drugs across the BBB. Transcytosis is put forward as one mechanism of drug loaded nanoparticles across the blood brain barrier (BBB). However little is known about it. Electron microscopy is an important method in the investigation on nanoparticles injected into the experimental mice. In this study it was found by fluorescence microscope that fluorescence existed along the capillary dissepiment. Some nanoparticles distributed in the brain capillary endothelial cells and brain tissue outside the microvaculum, which was observed by transmission electron microscopy. These particles were proved to be the Copper chlorophyll loaded nanoparticles which containing Cu detected by AEM. The in vivo experiments demonstrated directly that the PLA nanoparticles can pass the BBB indeed and transcytosis by microvascular endothelial cells may be the mechanism. The results provided an efficient way of drug delivery targeting the brain. Copper chlorophyll could be used as a new symbol of nanoparticles in in vivo experiment.