Moyes S M, Smyth S H, Shipman A, Long S, Morris J F, Carr K E
Department of Physiology, Anatomy and Genetics, Le Gros Clark Building, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom.
Int J Pharm. 2007 Jun 7;337(1-2):133-41. doi: 10.1016/j.ijpharm.2006.12.036. Epub 2007 Jan 7.
The hypothesis that, in vivo in situ, villous uptake of 2 microm latex microparticles involves changes at enterocyte tight junctions (TJs) was tested using Caco-2 cells on porous membranes. Epithelial permeability was measured by transepithelial resistance (TER) and particle numbers in surface, intraepithelial and sub-epithelial compartments by microscopy. Apical particle or medium addition initially closed TJs, but this was subsequently reversed in particle-treated groups. Peristaltic onward movement of a bolus was simulated by removing apical particles after an exposure period and leaving the remaining particles to interact with the epithelium: this produced marked TJ loosening during the interaction period. For particle exposure groups, the early similarity with particle numbers in vivo taken up in young adult rats became less marked with time, although bolus removal counteracted this tendency. The TJ response to vasoactive intestinal polypeptide (VIP) was time-dependent. Adsorbed and intraepithelial particle numbers increased with particle exposure time; epithelial-associated microparticle aggregation varied with treatment and submembranous particles were seen in all groups. Correlation between TER changes and particle numbers suggests TJ loosening may be important in microparticle uptake. This Caco-2 model gives epithelial particle numbers that approximate well to published figures for microparticle uptake in vivo and allows effective microenvironmental manipulation.
使用多孔膜上的Caco-2细胞测试了以下假说：在体内原位，2微米乳胶微粒的绒毛摄取涉及肠上皮细胞紧密连接（TJ）的变化。通过跨上皮电阻（TER）测量上皮通透性，并通过显微镜检查表面、上皮内和上皮下隔室中的微粒数量。顶端添加微粒或培养基最初会封闭紧密连接，但随后在微粒处理组中这种情况会逆转。在暴露期后去除顶端微粒并让剩余微粒与上皮相互作用，以此模拟团块的蠕动向前运动：这在相互作用期间导致了明显的紧密连接松弛。对于微粒暴露组，尽管去除团块抵消了这种趋势，但随着时间的推移，与年轻成年大鼠体内摄取的微粒数量在早期的相似性变得不那么明显。紧密连接对血管活性肠肽（VIP）的反应是时间依赖性的。吸附的和上皮内的微粒数量随着微粒暴露时间增加；上皮相关的微粒聚集因处理而异，并且在所有组中都观察到了膜下微粒。TER变化与微粒数量之间的相关性表明紧密连接松弛可能在微粒摄取中起重要作用。这个Caco-2模型给出的上皮微粒数量与已发表的体内微粒摄取数据非常接近，并且允许进行有效的微环境操作。
