Felsenstein Medical Research Center, Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv 69978, Israel.
ACS Nano. 2017 Nov 28;11(11):10883-10893. doi: 10.1021/acsnano.7b04495. Epub 2017 Oct 5.
Exosomes are emerging as effective therapeutic tools for various pathologies. These extracellular vesicles can bypass biological barriers, including the blood-brain barrier, and can serve as powerful drug and gene therapy transporters. However, the progress of therapy development is impeded by several challenges, including insufficient data on exosome trafficking and biodistribution and the difficulty to image deep brain structures in vivo. Herein, we established a method for noninvasive in vivo neuroimaging and tracking of exosomes, based on glucose-coated gold nanoparticle (GNP) labeling and computed tomography imaging. Labeling of exosomes with the GNPs was achieved directly, as opposed to the typical and less efficient indirect labeling mode through parent cells. On the mechanistic level, we found that the glucose-coated GNPs were uptaken into MSC-derived exosomes via an active, energy-dependent mechanism that is mediated by the glucose transporter GLUT-1 and involves endocytic proteins. Next, we determined optimal parameters of size and administration route; we demonstrated that 5 nm GNPs enabled improved exosome labeling and that intranasal, compared to intravenous, administration led to superior brain accumulation and thus enhanced in vivo neuroimaging. Furthermore, using a mouse model of focal brain ischemia, we noninvasively tracked intranasally administered GNP-labeled exosomes, which showed increased accumulation at the lesion site over 24 h, as compared to nonspecific migration and clearance from control brains over the same period. Thus, this exosome labeling technique can serve as a powerful diagnostic tool for various brain disorders and could potentially enhance exosome-based treatments for neuronal recovery.
外泌体正在成为各种疾病的有效治疗工具。这些细胞外囊泡可以绕过生物屏障,包括血脑屏障,并可作为强大的药物和基因治疗载体。然而,治疗发展的进展受到几个挑战的阻碍,包括外泌体运输和生物分布的信息不足,以及难以在体内对深部脑结构进行成像。在此,我们建立了一种基于葡萄糖包覆金纳米粒子(GNP)标记和计算机断层扫描成像的非侵入性体内神经影像学和追踪外泌体的方法。通过主动、能量依赖的机制,通过葡萄糖转运蛋白 GLUT-1 并涉及内吞蛋白,将 GNPs 直接标记到外泌体上,而不是通过亲本细胞进行典型的和效率较低的间接标记模式。在机制水平上,我们发现葡萄糖包覆的 GNPs 通过一种主动、能量依赖的机制被摄取到 MSC 衍生的外泌体中,该机制由葡萄糖转运蛋白 GLUT-1 介导,并涉及内吞蛋白。接下来,我们确定了大小和给药途径的最佳参数;我们证明了 5nm 的 GNPs 能够改善外泌体标记,与静脉内给药相比,鼻内给药可导致更好的脑内积累,从而增强体内神经影像学。此外,在局灶性脑缺血的小鼠模型中,我们非侵入性地追踪了经鼻内给予的 GNP 标记的外泌体,与同一时期对照脑的非特异性迁移和清除相比,其在损伤部位的积累增加了 24 小时。因此,这种外泌体标记技术可以作为各种脑疾病的强大诊断工具,并有可能增强基于外泌体的神经元恢复治疗。