Abstract 012: Aorta-on-a-chip: a Tool to Gain Molecular and Translational Insight Into Vascular Diseases

Abstract

Vascular cell biology research is focused on understanding how endothelial cells and smooth muscle cells react to relevant biological, chemical and physical stimuli. Importantly, in vivo , dynamic conditions are present: vascular endothelial cells (ECs) are constantly subjected to shear stress and smooth muscle cells (SMCs) are stretched due to pulsation during the cardiac cycle. A three-dimensional network composed of extracellular matrix proteins maintains the homeostasis of the cells. The aim of this project is to realize an in vitro model of the human aorta ( aorta-on-a-chip ), an innovative tool that by resembling the in vivo structure of the aorta allows us to study how cells layers and matrix are sensing and responding to a pro-atherogenic environment (i.e. low shear stress) and to gain insight in the pathological remodeling occurring during progression of vascular diseases. The device consists of two re-sealable glass slides, assembled with a membrane suspended in between them, which creates two separate flow chambers. After coating both sides of the membrane with fibronectin, ECs and SMCs are seeded sequentially, in order to obtain a confluent ECs-SMCs co-culture, mimicking the intima-media interface of the aortic wall. The co-culture device is connected to a microfluidic pump system where ECs are exposed to physiologically relevant shear stress (8-12 dyne/cm 2 ). The SMCs flow-chamber is exposed to a low shear stress (0.0042 dyne/cm 2 ) to ensure physiological turnover of influx of nutrients and efflux of waste. Molecular and phenotypic evaluation of the cells is performed by measuring gene expression changes (RNA sequencing) and protein analyses (immunofluorescence for cell markers), respectively. For translational purposes, cells deriving from patients with aortic diseases (compared to un-diseased organ donor controls) can be implemented and tested with the chip.