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Nicolas Villa-Roel
BME PhD Defense Presentation
Date: 2022-10-19
Time: 2:00 PM
Location / Meeting Link: Emory University Hospital, Hurst Conference Room E-450 / https://emory.zoom.us/j/91625299517
Committee Members:
Hanjoong Jo, PhD (Advisor) – GT/Emory BME; Ajit Yoganathan, PhD – GT/Emory BME; W. Robert Taylor, MD, PhD – GT/Emory BME; David Myers, PhD – GT/Emory BME; Greg Gibson, PhD – GT Biological Sciences; Vinod Thourani, MD – Piedmont Cardiothoracic Surgery
Title: Defining the Pathogenic Mechanisms of Calcific Aortic Valve Disease through Single-Cell RNA Sequencing
Abstract:
Calcific Aortic Valve Disease (CAVD) is an active, multifactorial disease ranging from mild thickening and hardening of the aortic valve (AV) leaflets to severe impairment of leaflet motion, inducing AV stenosis. Currently, there are no treatment alternatives for CAVD aside from surgical or transcatheter AV repair or replacement with bioprosthetic or mechanical substitutes, highlighting the need for novel therapeutics to prevent and manage the progression of the disease. Interestingly, CAVD occurs preferentially in a side-dependent manner, with most of the pathology appearing on the fibrosa layer of the AV, facing the aorta, and exposed to complex, disturbed flow conditions. This dissertation aimed to define the mechanisms by which side-dependent CAVD occurs using a single-cell RNA sequencing (scRNAseq) approach and validation studies. Previous scRNAseq and proteomics approaches have examined the disease development of the AV; however, these methods required digestion of the whole AV tissues, making it impossible to determine side-specific differences or changes occurring in flow-sensing, valvular endothelial cells (VEC) due to the sampling bias towards more prevalent cell populations. We hypothesized that our side-dependent, single-cell isolation procedure using human AV leaflets would produce single cell samples including enough VEC from both sides of the AV, thus enabling a scRNAseq study to reveal genome-wide transcriptome patterns for the heterogeneous AV cell clusters in a side-specific manner at a single-cell resolution. In-depth in silico analysis of the scRNAseq results were carried out using computational and bioinformatics tools to identify unique cell clusters, genes, pathways, and interactomes as a function of disease development. Key differentially expressed genes with potential significance to the pathophysiology were further validated in vitro and in human AV tissues. This dissertation provides a deeper understanding of the AV microenvironment and cellular heterogeneity, enabling us to unveil several side-dependent and disease-dependent genes which may serve as potential therapeutic targets.
