Stacked, paper-based culture models of heart valve layers: effects of hypoxia gradients and heterogeneous extracellular matrix

William Marsh Rice University, Houston TX

Investigators

Abstract

PI: Grande-Allen, Kathryn J. Proposal Number: 1404008 Institution: William Marsh Rice University Title: Stacked, paper-based culture models of heart valve layers: effects of hypoxia gradients and heterogeneous extracellular matrix Heart valve disease affects hundreds of thousands of people of all ages and socioeconomic classes worldwide. Given the growing association of calcific aortic valve disease with aging, diabetes, and metabolic syndrome, the treatment of just this disease alone represents significant health care costs now and in the future. Currently, valve diseases can only be treated through surgical or interventional means; there is no pill one can take to prevent or reverse valve disease. It is unclear exactly how valve diseases get started or how they worsen. Since the interactions between the cells and the material surrounding the cells - like collagen and complex carbohydrates - appear to play an important role in the health of the valve, as well as in the diseases, the PI has developed a unique way to study these interactions. The use of advanced, innovative approaches to grow the valve cells in an environment mimicking a normal, healthy or diseased valve will provide significant new information on the fundamental biology of heart valves and will help understand the disease process and test new non-surgical therapies. In addition, the goals and activities of this research will be distributed to a broad audience of students (ranging from high school to graduate school) as well as high school teachers. The function of heart valves is made possible by the unique microstructural arrangement of extracellular matrix (ECM) components within the tissue. Many groups including the PI's have begun to investigate how ECM fundamentally regulates valve cell and tissue behavior, often using 2D cell cultures and immunohistochemistry, but these methods can be time-consuming and provide limited insight into active tissue remodeling. Cell culture environments such as hydrogels or fibrous scaffolds constructed from ECM or synthetic polymers offer cells a 3D environment that can be highly biomimetic, but analysis of the cell behavior throughout the entire thickness of the 3D scaffold is challenging. Thus, the proposed studies will evaluate the normal and pathological behavior of valvular ECM and valvular interstitial cells (VICs) using the new field of paper-based cell culture technology. In particular, stacks of paper impregnated with gel scaffolds are appealing for high throughput, automated analysis of cell behavior throughout the stack, and can be used to evaluate the effects of hypoxia. Indeed, this technology is exceptionally well suited to investigate VIC-ECM relationships. More specifically, this technology will be used to assemble stacks of papers - each impregnated with a different ECM-based gel scaffold - into a layered structure that mimics the heterogeneous layered structure of the heart valve. This method will allow several in-depth studies to examine the effects of certain types of extracellular matrix, the amount of oxygen the cells are receiving, and the heterogeneous layered nature of heart valves, on the phenotypic and signaling behavior of the valve cells. These responses will be evaluated and compared for two original heart valve sources of the VICs (aortic vs. mitral valve). The overall goal of the work is to evaluate the normal and pathological responses of VICs to ECM and hypoxia. It is expected that this unique experimental system will generate insight regarding the fundamental behavior of valve cells and how this behavior can be regulated, which will be impactful on developing new therapies for disease and the design of tissue engineered valves.