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Title:Lung-on-a-chip device with in situ imaging capabilities
Author(s):Sinclair, Whitney Elaine
Director of Research:Kenis, Paul J.A.; Leckband, Deborah E.
Doctoral Committee Chair(s):Kenis, Paul J.A.
Doctoral Committee Member(s):Murphy, Catherine J.; Kong, Hyun Joon
Department / Program:Chemical & Biomolecular Engr
Discipline:Chemical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
confocal imaging 'on-chip'
pressure regulator
gold nanoparticles
endothelial cell actin organization
Abstract:Engineered tools can be used for biological studies that investigate the interplay between mechanical forces and cell biology. More specifically, lung-on-a-chip microfluidic platforms offer increasingly sophisticated methods to study the in vivo lung response. These platforms do so by applying hydrodynamic and mechanical forces to pulmonary lung tissue to mimic the physiological environment within the alveolar-capillary interface. In this dissertation, I outline the development of a lung-on-a-chip platform that enables ex-vivo studies under active physio-mechanical stress to vascular endothelial cells. Lung-on-a-chip platforms can be used to study lung cell biology, disease states, pre-clinical drug response, and/or the effects of environmental pollutants (e.g., nanoparticles). Chapter 2 of this thesis investigates the impact of gold nanoparticles on the metabolic activity and morphology of human pulmonary endothelial cell monolayers. Nanoparticles are moving towards use as consumer products and therapeutic agents, and are gaining prevalence as environmental toxins. This has led to increasing concern for the impact that nanoparticles have on human health, specifically the lung. To study some of these effects, a gold nanoparticle library was developed including nanoparticles with three different sizes and two surface chemistries (citrate and poly(allylamine hydrochloride)). To stabilize the nanoparticles in cell culture medium, a bovine serum albumin pretreatment protocol was developed. The development of the nanoparticle library and pretreatment protocol was performed in collaboration with the Murphy research group at the University of Illinois at Urbana-Champaign. I performed a colorimetric assay to determine the effect the nanoparticle library has on human pulmonary artery endothelial cell metabolic activity. Then, I used subcellular imaging to observe the morphological impact of acute gold nanoparticle exposure on endothelial actin networks and intercellular gaps. While gold nanoparticles only modestly affect endothelial metabolic activity, exposure of primary vascular endothelial cells to citrate- or poly(allylamine hydrochloride)-coated gold nanoparticles resulted in cortical actin remodeling and an increase in intercellular gap formation. I was also able to identify that the bovine serum albumin pretreatment helped to mitigate the negative effects of free or bound polyelectrolytes on endothelial monolayers. The fabrication approach and design reported in Chapter 3 aims to improve accessibility of organ-on-a-chip technology to the broader biomedical research community. Access to current lung-on-a-chip platforms is hampered by the need for advanced fabrication techniques to create these platforms, and the need for extensive ancillary equipment for their operation. I report the use of dual layer lithography to significantly reduce the technical expertise and equipment required to create porous, stretchable membranes. A cost effective, portable pressure regulator was developed to apply physiologically relevant cyclic stretch (to resemble breathing) across cells grown on the porous membrane. I incorporated cyclic olefin copolymer sheets into the microfluidic platform design to reduce the total device thickness to enable fluorescence imaging ‘on-chip’. Furthermore, the reversible bond between the polydimethylsiloxane platform and the cyclic olefin copolymer lid allows for exposure of the cells to aerosolized particulates using a nebulizer. The lung-on-a-chip platform outlined in this dissertation takes advantage of Arduino technology for application of cyclic stretching to cells and traditional photo/soft lithography techniques to reduce equipment requirements, while allowing for imaging ‘on-chip’. Chapter 4 reports the capacity to image cells in situ on the lung-on-a-chip platform. I obtained subcellular, actin images ‘on-chip’ of bovine aortic endothelial cells and human pulmonary aortic endothelial cells. I also validated the platform with respect to its ability to apply shear stress and cyclic stretch in vitro to confluent layers of endothelial cells, mimicking the in vivo microenvironment. Using ‘on-chip’ imaging, I characterized the impact of physiologically relevant shear stress and cyclic stretch on endothelial cell morphology. Specifically, in vitro morphological alignment was used as a marker for recapitulating in vivo cell behavior. The accessible lung-on-a-chip platform outlined in this dissertation can be used in a wide variety of biological studies, ranging from mechanobiology experiments to studying the impacts of environmental pollutants or pharmaceuticals on bilayers of pulmonary epithelial and endothelial cells.
Issue Date:2021-12-02
Rights Information:Copyright 2021 Whitney Sinclair
Date Available in IDEALS:2022-04-29
Date Deposited:2021-12

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