Cardiovascular Bioengineering

Several BME investigators work in the area of Cardiovascular Bioengineering in studies of blood vessels and heart valves, especially in interaction with implanted prostheses. Linda M. Graham, M.D., seeks to design longer-lived tissueengineered vascular grafts. Her group investigates, at the molecular level, how smooth-muscle cells (SMCs) and collagen affect cell proliferation and ingrowth into prosthetic grafts, including: 1) the molecular mechanisms involved in the posttranscriptional regulation of collagen secretion by graft SMCs, 2) the mechanism by which oxidized LDL inhibits endothelial cell migration, and 3) the effect of hypercholesterolemia on endothelial cell ingrowth onto prosthetic grafts in vivo. Scott Colles, Ph.D., focuses on the role of glutathione peroxidase and lipid oxidation products in the development of vascular disease. Lipid oxidation products are thought to be major factors in the development of various vascular diseases including atherosclerosis. Roy Greenberg, M.D., joint staff with the Department of Vascular Surgery, focuses on the development of novel techniques and endovascular devices (e.g., stents and stent grafts) to treat aortic aneurysms and dissections, a significant threat to the aging population. His aim is to ward off the main complication of endovascular repair, the development of early or late endoleak, which remains undetected by conventional clinical methods. The Heart Valve Laboratory team led by Ivan Vesely, Ph.D., studies the structure/function relationship of heart valve tissues to determine failure mechanisms of manufactured replacement heart valves, with the aim of developing a bioprosthetic valve that completely mimics the natural valve’s function. The group uses materials testing, mathematical modeling, microscopy, biochemical analysis, and cell culture, along with micromechanical testing, video image processing, and extensions to Fung’s original Quasi-Linear Viscoelastic theory. In collaboration with NASA researchers, they are developing advanced soft-tissue models for simulating robotic surgery in a virtual-reality training system. The group also addresses genetic and biomechanical characteristics of aortic valves affected by myxomatous mitral valve disease, a condition characterized by thickening of valve tissues and stretching of leaflets and chordae, causing the valve to leak. The group is also creating tissue-engineering implants of elastin, collagen and glycosaminoglycans synthesized by cells in culture or purified from tissues, then manipulated to mimic the aortic valve’s normal structural framework. Dr. Geoffrey Vince’s work also contributes to this area of emphasis.