Title: A Biomimetic Microfluidics Platform for High-Throughput Screening of Endothelial Barrier Dysfunction, with Applications to Atherosclerosis
Funder: Engineering and Physical Sciences Research Council

Abstract: All blood vessels in your body are lined with a continuous layer of endothelial cells. These cells create a semi-permeable barrier that separates blood from all other tissues in the body, and any molecule passing between blood and tissue must cross this endothelium. The endothelium therefore lies at a critical interface where it functions as "gatekeeper" to regulate the transport of water, cells and nutrients between blood and all extravascular tissues in the body. Disruption of the endothelial barrier contributes to the pathogenesis of disease such as lipid accumulation in the artery wall in atherosclerosis, tissue swelling in oedema, vascular leakage in inflammation, and metastasis in cancer. Thus, maintaining the endothelial barrier is a critical aspect of homeostasis, but our understanding of the endothelial barrier is still incomplete. Endothelial cells and the barrier that they create are exquisitely sensitive to mechanical forces. Typically these forces arise from shear or viscous drag caused by blood flowing over the endothelial cells and stretch imposed on the wall by blood pressure. In combination with chemical factors, shear and stretch regulate diverse aspects of endothelial function (e.g., both affect alignment, contractility, and the strength of cell-cell connections). The mechanical sensitivity of endothelial cells is also involved in atherosclerosis, the leading cause of cardiovascular disease, heart attacks and strokes that affects millions of people annually. In atherosclerosis, altered mechanical forces arising from disturbed blood flow are believed to contribute to dysfunction of endothelial barrier, leading to infiltration and accumulation of lipid in the artery wall. Other theories describe how lipid infiltration may be related to the disturbances in stretch experienced by the endothelium. Investigating these hypotheses, however, requires that we have a reliable tool to measure the rate of transport across the endothelium in response to different levels of shear and stretch. In this project, we develop a micro-fluidics based technology to examine how shear stress and stretch affect endothelial permeability, the parameter controlling lipid infiltration into the artery wall during the early stages of atherosclerosis. Our design overcomes several limitations of previous in vitro models by allowing independent and simultaneous control of both shear and stretch over the physiological range, while providing a quantitative readout of permeability that can be measured in real-time. The design of the microfluidics platform is fully scalable to allow for high-throughput screening or parallel experimentation. In this project, we will develop and characterise the microfluidics device. We will validate the device by demonstrating that it is able to reproduce standard measurements of endothelial permeability in the absence of shear and stretch. Finally, we will use the device to determine the effect of combined shear and stretch on endothelial permeability.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS;2.5 RESEARCH DESIGN AND METHODOLOGIES (AETIOLOGY)
Health categories: CARDIOVASCULAR