The K01 will facilitate Dr. Ebong's development of her independent research position as a tenure-track professor. Her research objective is to combine engineering with advanced microscopy, cell and molecular biology, and animal pathophysiology to elucidate endothelial cell (EC) glycocalyx (GCX) ultrastructure and its functional role in EC mechanotransduction and vascular function in health and atherosclerosis. With her background in core engineering theory and practice, and her solid interdisciplinary research experience that blends cardiovascular and cellular bioengineering with molecular biology, Dr. Ebong is highly qualified to carry out the Research Strategy and meet the Career Goals and Objectives. This award will enable her to expand her research, enhance its interpretation, and produce new discoveries. Dr. Ebong will be mentored by an interdisciplinary team that has broad expertise in bioengineering, in vitro and in vivo shear and mechanotransduction experiments, in vivo modeling of vascular pathology, glycobiology, microscopy, anatomy and structural biology, and molecular biology. The make-up of this team will provide her with an extensive network of techniques, facilities, and research institutions. The mentored activities proposed for this K01 program will be primarily conducted at Northeastern University and performed in Dr. Ebong's laboratory. Faculty and facilities of Northeastern (Drs. Ruberti, Khaw, and Hancock), The City College of New York (Dr. Tarbell), Albert Einstein College of Medicine (Mr. Macaluso), Emory University School of Medicine and Georgia Institute of Technology (Dr. Jo), Temple University School of Medicine (Dr. Rizzo), and University of California at San Diego (Dr. Esko) will also support Dr. Ebong's training. Atherosclerosis occurs at blood vessel sites, such as branches, where unstable (disturbed) flow makes the endothelial cell (EC) layer dysfunctional. Healthy tissue lines straight blood vessels where streamlined (uniform) flow permits normal EC function. The mechanisms by which flow alters EC function to prevent or promote atherosclerosis remain unclear. Defining these mechanisms is the primary focus of Dr. Ebong's research program. The K01 research strategy proposed by Dr. Ebong and her team is to study the structure and function of a prime EC mechanotransducer candidate-the surface glycocalyx (GCX)-which directly senses flow, can transmit force via the cytoskeleton to various biologically active cellulr sites, and sheds in atherosclerosis. GCX is essential for flow conversion to EC functions including nitric oxide (NO) release, cytoskeleton organization, gap junction communication, and cell shape that are abnormal in atherosclerosis. Dr. Ebong has already shown that flow induces vasoregulatory EC-type NO synthase (eNOS) activation, but only in the presence of the heparan sulfate (HS) glypican-1 (GPC-1) component of the EC GCX. Her work has revealed that flow-induced EC remodeling relies on the HS syndecan-1 (SDC-1) component of the GCX. Using rapid freezing/freeze substitution (RF/FS) transmission electron microscopy (TEM), she is currently defining the EC GCX ultrastructure and its changes due to cellular origin and the biochemical and flow environment. During the period of the K01 award, Dr. Ebong and her team will advance this work by testing the hypothesis that EC respond differently to uniform and disturbed flow through dynamic changes in GCX ultrastructure (Aim 1), which trigger the caveolae and cytoskeleton (and subsequently, the gap junctions and basal matrix) to differentially activate EC signaling and remodeling events (Aim 2) that lead to vascular health or disease (Aim 3). This hypothesis will be tested using cultured EC with intact or manipulated GCX, which are subjected to atheroprotective and atherogenic flow conditions that are replicated in vitro using a parallel plate flow chamber. Mouse models of GCX component deletion, acute disturbed flow, endothelial and vascular dysfunction, and atherosclerosis will also be employed. Flow-induced GCX thickness, morphology, and subcomponent content and organization will be assessed. Flow- and GCX-regulation of EC signaling and remodeling events such as eNOS activation and NO production, connexin-specific gap junction signaling, and remodeling of cell shape and basal adhesions will be examined. GCX component-specific involvement in EC- dependent vasoregulation, the development of robust atherosclerosis, and the determination of lesion complexity will also be studied. The team expects to identify GCX components that are biomarkers of atherosclerosis. The findings of this research will be essential for engineering new diagnostics and therapeutics that target the EC GCX to combat atherosclerosis. Dr. Ebong is talented, the mentoring and research team is experienced and interdisciplinary, and the research strategy is exciting and innovative. Without a doubt, Dr. Ebong will emerge from the K01 as an independent investigator with a unique identity, a wide-range of powerful research tools, a robust research infrastructure, and a voice in high-level discourse on GCX-related approaches to the prevention, diagnosis, and treatment of atherosclerosis.
Atherosclerosis is the underlying cause of the majority of heart attacks, strokes, aneurysms, and peripheral vascular disorders that constitute the most widespread medical and surgical problems and claim the lives of almost half the people in the United States and Europe. This research will greatly improve our understanding of the mechanisms by which the glycocalyx coat on blood vessel wall endothelial cells promotes vascular health or leads to atherosclerosis when it is degraded. The findings of this research will lead to the development of new tools that target the glycocalyx to prevent, diagnose, and treat atherosclerosis.
