DYNAMICALLY-LOADED 3-D MODEL TO STUDY THE ECM ORGANIZATION OF AORTIC SMOOTH MUSCLE CELLS IN ANEURYSMAL PATIENTS WITH BICUSPID AORTIC VALVE

摘要

Rupture of aortic aneurysms and dissections are the fifteenth leading cause of a death in the United States [1]. Over 40% of patients undergoing elective surgery for ascending aortic replacement due to thoracic aortic aneurysm (TAA) have a congenital defect in the aortic valve know as bicuspid aortic valve (BAV) [2]. BAV patients have uniformly larger diameter aortic roots and ascending aortas compared to age- and sex-matched controls [3] and abnormal elasticity even in the absence of valvular stenosis or aneurysm [4] and this greatly increases the risk of aortic dissection and sudden death [5]. The cause of TAA is uncertain, but recent studies suggest that oxidative stress may play a role in the pathogenesis of TAAs by degrading the extracellular matrix (ECM). We identified that BAV smooth muscle cells (SMCs) lack sufficient resistance to reactive oxygen species to maintain ECM homeostasis [6, 7]. In the body, cell-cell and cell-ECM communications are established within a 3-D network to maintain tissue homeostasis [8]. Investigations of aortic SMC behaviors have been limited to 2-D models, which distinctly restrict one's ability to study the organized deposition of elastin and collagen that exist in a 3-D environment in vivo. To overcome the limitation of 2-D culture, we developed the 3-D dynamically-loaded fibrin gel culture model to study the impact of oxidative stress on deposition and organization of the ECM produced by primary aortic SMCs in vitro. Fibrin is known to stimulate the secretion of reinforcing ECM proteins by seeded cells [9]. The effect of mechanical stimuli such as cyclic stretch has been widely studied to play a major role in SMC differentiation and pathology [10]. The objective of this study is to investigate the ECM deposition and organization of SMCs in aneurysmal patients with BAV. Additionally, the study will determine the dose of stress which will result in moderate oxidative stress without excess cell death.