Membrane-integrated glass chip for two-directional observation of epithelial cells

Abstract

The investigation of the basic properties of epithelial cells, such as the observation of the morphology and evaluation of the barrier function, is important for pharmacotherapeutic applications. These investigations are traditionally achieved by culturing epithelial cells on Transwell filters. However, the cross section of the cell layer cannot be directly observed with this method, and the permeability measurement requires many steps. Herein, we developed a glass microfluidic chip sandwiching a porous PET membrane between two glass capillaries and present a model with two advantages over conventional models: 1) direct top-view and cross-sectional observation of the cell layer and 2) facile assessment of the epithelial permeability without laborious manual sampling. We designed and fabricated a glass microfluidic chip and evaluated its characteristics. We then cultured the epithelial cells in the chip to demonstrate the observation of the cell layer in both the x–y and x–z planes under a microscope. Furthermore, we measured the permeation of the fluorescence probe through a human trophoblast cell layer cultured on the chip without manual sampling. We believe that our chip would be a powerful tool for analysis of the epithelial cells with high usability.