CURRENT RESEARCH
What We Do
Endothelial cells regulate vascular homeostasis from their unique position at the blood-tissue interface. In this complex environment, endothelial cells dynamically integrate biochemical and mechanical stimulation from the flowing blood at their apical surface and the vascular wall at their basolateral surface. Disturbances in the biochemical and biomechanical environment, such as elevated glucose or low shear stress, can lead to endothelial dysfunction and subsequent cardiovascular disease.
The Vascular Kinetics Laboratory conducts research at the interface of engineering, biochemistry, and vascular biology. In our prior work, we largely focused on how an altered glucose environment (e.g., in diabetes) impaired endothelial cell response to shear stress and cyclic strain. We demonstrated that endothelial cells in high glucose do not respond appropriately to mechanical stimuli. Today, we focus primarily on the opposite question- how the mechanical environment affects endothelial cell glucose metabolism. We are integrating mechanobiology and metabolism, with the hope of using metabolic engineering to decrease the burden of cardiovascular disease and cancer. With new collaboration opportunities at the University of Maryland, we plan to extend our cell and animal work into human studies.
RESEARCH PROJECTS
Laminar and Disturbed Flow Effects on Endothelial Glucose Metabolism
Laminar and Disturbed Flow Effects on Endothelial Glucose Metabolism
Endothelial metabolism has recently emerged as a powerful tool to regulate the abnormal microvasculature in cancer. When glycolysis is blocked, endothelial cells are no longer able to form new blood vessels in vitro or in vivo. However, little is known about how endothelial cell metabolism impacts macrovascular endothelial function in health and disease. When arterial endothelial cells adapt to steady laminar flow, they express a quiescent phenotype, maintaining vascular homeostasis through tight control of proliferation, permeability, inflammation, and vascular tone. When endothelial cells fail to adapt to flow, for example in areas of oscillating disturbed flow, they maintain a round morphology with elevated proliferation, permeability, and inflammatory adhesion molecule expression as well as impaired nitric oxide (NO) production (collectively defined as endothelial dysfunction). These disturbed flow regions are linked to subsequent vascular pathology, including atherosclerotic plaque development. Our goal is to understand how vascular hemodynamics regulates endothelial glucose metabolism, and how endothelial glucose metabolism can be modulated to reduce endothelial dysfunction in disturbed flow. Our data show that endothelial cells decrease glycolytic flux in steady laminar but not oscillating disturbed flow. Our data also show that steady laminar and oscillating disturbed flow differentially regulate side branches of glycolysis including the hexosamine biosynthetic pathway, which controls the post-translational protein modification O-GlcNAcylation. The goal of this project is to understand how steady laminar and oscillating disturbed flow differentially affect macrovascular endothelial glycolytic flux. We further aim to determine how these metabolic pathways impact endothelial dysfunction in vitro and ex vivo.
Computational Models of Endothelial Metabolism
Cellular metabolism is a complex, branched, recursive network with many interlinked pathways through which multiple metabolites are used to create energy for the cell as well as a multitude of other purposes (e.g., amino acid synthesis, post-translational protein modifications, oxidative stress reduction). While some groups have postulated that blocking one metabolic pathway (e.g., glycolysis) will inhibit a specific cell function (e.g., angiogenesis), we believe that we must first understand the system-level effects of metabolic inhibitors on the entire metabolic network to effectively create metabolic therapies. We are therefore using a combination of experimental and computational techniques to understand how metabolism is perturbed under different conditions. In order to quantify alterations in metabolic flux from experimental samples, we are utilizing a technique known as metabolic flux analysis. By incorporating measured extracellular fluxes, metabolite isotopomer distributions, and simplified metabolic maps in computational models, we can infer the metabolic fluxes of our experimental samples. These results can be further extended to develop predictive metabolic models. By utilizing RECON3D, together with endothelial gene expression data sets and inferred fluxomic distributions, we are developing a computational model of endothelial cell metabolism that can predict how metabolism is altered under conditions such as substrate depletion or pharmacological treatment. In the future, we hope to expand this computational model to better understand how endothelial cells use and transport metabolites in concert with surrounding parenchymal cells, for example to better understand changes in glucose metabolism in diseases such as cancer and Alzheimer’s..
Arterial stiffness in spinal cord injury
Cardiovascular disease is the leading cause of death in the chronically spinal cord injured (SCI) population. Individuals with SCI have a two-fold greater risk of heart disease compared to those without SCI, which is similar to the risk incurred by smoking or diabetes. The increased cardiovascular disease risk in individuals with SCI is often attributed to the increased prevalence of cardiovascular disease risk factors as well as autonomic nervous system dysfunction and physical inactivity. However, individuals with SCI also have stiffer arteries than able-bodied controls with similar age, weight, blood pressure, and physical activity. Arterial stiffness, which is determined by vascular tone and extracellular matrix remodeling, is an independent predictor of cardiovascular risk. Our goal is to understand the mechanisms underlying increased cardiovascular risk in the chronic SCI population. Our preliminary data show that aortic stiffness increases in a mouse SCI model as early as 4 weeks after injury. The change in arterial stiffness may relate to changes in inflammation, sympathetic nervous system activity, and extracellular matrix imbalances. These studies have potential to lead to new cardiovascular treatments in the SCI population and well as in non-SCI patients with systemic inflammation, since arterial stiffness can be readily measured by pulse wave velocity and FDA-approved inflammatory inhibitors are available.
Blood
The blood-brain barrier is primarily comprised of brain microvascular endothelial cells (BMECs). These cells are distinct from other endothelial cells as they express tight junction proteins that seal adjacent cells together, allowing them to form a highly selective barrier that restricts movement of substances into the brain. In addition, BMECs play a critical role in supplying glucose and other essential metabolites to the brain by selectively shuttling glucose into the brain. Alterations in brain endothelial cells can lead to breakdown of the blood-brain barrier, which may alter nutrient availability and allow for infiltration of neurotoxic or inflammatory compounds into the brain. Notably, dysfunction of brain endothelial cells has been implicated in many neurological diseases, such as Alzheimer’s, Parkinson’s, multiple sclerosis, and stroke. Using tools such as induced pluripotent stem cell-derived (iPSC) BMECs and CRISPR-Cas9 gene editing, we seek to understand how metabolic disturbances may lead to BMEC dysfunction and potentially contribute to neurological disease progression. In addition, we recently published our findings detailing key similarities and differences between iPSC-derived BMECs and primary BMEC metabolism.
Current Funding Sources
