Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University , Beijing 100191, China.
Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States.
ACS Appl Mater Interfaces. 2017 Feb 22;9(7):5803-5816. doi: 10.1021/acsami.6b15151. Epub 2017 Feb 9.
Drug nanocrystals (NCs) appear to be favorable to improving oral bioavailability of poorly water-soluble drugs as evidenced by the great success they have had in the market. However, the pathway and mechanism of drug NCs through epithelial membrane are still unclear. In an attempt to clarify their transport features, paclitaxel nanocrystals (PTX-NCs), and paclitaxel hybrid NCs with lipophilic carbocyanine dyes, were prepared and characterized as the models. The endocytosis, intracellular trafficking, paracellular transport, and transcytosis of PTX-NCs were carefully investigated with Förster resonance energy transfer (FRET) analysis, as well as a colocalization assay, flow cytometry, gene silencing, Western-blot, transepithelial electrical resistance (TEER) study and other approaches on MDCK cells. It was found that rod-like PTX-NCs could transport through the monolayer intact, and the process of endocytosis proved to be time and energy dependent. Endoplasmic reticulum (ER) and Golgi complexes were colocalized with PTX-NCs in cells, so the ER-Golgi complexes/Golgi complexes-basolateral membrane pathway may be involved in the intracellular trafficking and transcytosis of PTX-NCs. It was demonstrated here that cav-1, dynamin, and actin filament modulated the endocytosis process, and Cdc 42 regulated the transcytosis process. In addition, no paracellular transport of PTX-NCs was observed. These findings demonstrated that the rod-like nanocrystals not only enhanced the transcytosis of PTX compared with microparticles of raw drug materials but also changed the pathways of drug delivery. This study certainly provides insight for the oral absorption mechanism of nanocrystals of poorly soluble drugs.
药物纳米晶体（NCs）似乎有利于提高水溶性差的药物的口服生物利用度，这从它们在市场上的巨大成功中可以得到证明。然而，药物 NCs 通过上皮细胞膜的途径和机制仍不清楚。为了阐明它们的传输特征，制备并表征了紫杉醇纳米晶体（PTX-NCs）和具有亲脂性碳菁染料的紫杉醇混合 NCs 作为模型。通过荧光共振能量转移（FRET）分析、共定位测定、流式细胞术、基因沉默、Western blot、跨上皮电阻（TEER）研究和 MDCK 细胞上的其他方法，仔细研究了 PTX-NCs 的内吞作用、细胞内转运、旁细胞转运和转胞运输。结果发现，棒状 PTX-NCs 可以完整地穿过单层运输，内吞作用的过程是时间和能量依赖性的。内质网（ER）和高尔基体复合物与 PTX-NCs 在细胞中共定位，因此 ER-Golgi 复合物/高尔基体-基底外侧膜途径可能参与了 PTX-NCs 的细胞内转运和转胞运输。结果表明，cav-1、dynamin 和肌动蛋白丝调节内吞作用过程，Cdc42 调节转胞运输过程。此外，未观察到 PTX-NCs 的旁细胞转运。这些发现表明，棒状纳米晶体不仅增强了与原料药微颗粒相比的 PTX 转胞运输，而且改变了药物输送途径。这项研究为研究难溶性药物纳米晶体的口服吸收机制提供了一定的思路。
