Microfluidic airway on-chip

Abstract

Organs-on-chip are a new class of in vitro devices aimed at improving the predictivity of preclinical drug testing models by integrating physiologically relevant features in cell culture devices using microfabrication techniques. In human bodies, epithelial tissues are the first line of defence against the external environment and act as barriers by expressing inter-cellular protein complexes called tight junctions (TJ). The epithelial physical barrier has selective permeability properties which can experimentally be measured by electrical means. In this thesis, the design, simulation, modelling, optimisation, fabrication and experimental characterisation of a novel organ-on-chip device for epithelial cell culture and epithelial barrier monitoring are described. In the device, cells are cultured on top of a nanoporous support, fed by constant perfusion of growth medium and barrier properties are monitored in real-time with integrated coplanar Pt/Pt-black electrodes. Finite element method (FEM) simulations were used to develop a new coplanar electrode design which achieved greater sensitivity (45-fold) compared to the other coplanar designs presented in the literature. This design was formed by 2 circular segments electrodes divided by a polymeric septum. The high sensitivity of the novel electrode design enabled the measurement of epithelial electrical properties directly at the air-liquid interface (ALI) and was used to monitor disruptions in the barrier properties of primary bronchial epithelial cells (PBECs) cultured on commercial supports (Transwell®) induced by a calcium chelator (EGTA). The measured barrier disruption was comparable to those measured by standard systems without requiring a submerged culture. The microfluidic device was used to monitor the establishment of the physical barrier under submerged conditions for 6 days of the human bronchial epithelial cell line (16HBE14o-) and disruption of the physical barrier induced by stimulation with a viral mimic (poly(I:C)). All results were comparable to the ones measured by standard systems. This platform is an easy-to-manufacture alternative to available systems with the unique potential to enable the real-time epithelial barrier monitoring under submerged or ALI conditions.

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ORCID for Hywel Morgan: orcid.org/0000-0003-4850-5676

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