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Transmembrane Pathways and Mechanisms of Rod-like Paclitaxel Nanocrystals through MDCK Polarized Monolayer
journal contribution
posted on 2017-01-24, 00:00 authored by Feiyang Deng, Hua Zhang, Xing Wang, Yuan Zhang, Hongxiang Hu, Siyang Song, Wenbing Dai, Bing He, Ying Zheng, Xueqing Wang, Qiang ZhangDrug 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.