This project proposes a detailed investigation of the pathobiologic behavior of abdominal aortic aneurysms (AAAs). The investigators plan to construct individual phantoms of AAAs from CT scans of patients, and use the phantoms to analyze and characterize the flow patterns through the phantoms under both steady and pulsatile conditions. In the next phase of the project, arterial endothelial cells will be seeded on to the interior wall of the phantoms and allowed to multiply. Then the phantoms are tested under the specific flow and stress tests as determined earlier in the project. Finally, the cells are tested for certain selected markers which affect the arterial wall elasticity and the possibility of rupture. The project offers a balanced integration of engineering techniques, molecular biology and medicine.