Mechanobiological study of aortic elastin

Elastin fibers are one of the major ECM components that endow blood vessels critical mechanical properties such as flexibility and elasticity. They are essential to accommodate deformations encountered during physiological function of arteries, which undergo repeated cycles of extension and recoil. We have studied, both experimentally and theoretically, the mechanical properties of elastin under biaxial tensile loading. The orthotropic hyperelasticity of elastin was well captured by a statistical mechanics based microstructural constitutive model. The time-dependent behavior of elastin was studied using biaxial stress relaxation and creep testing. A quasi-linear viscoelasticity model was incorporated into the statistical mechanics based microstructural model at the fiber level to simulate its tissue level mechanical behavior. We have demonstrated the model is suitable to capture both the orthotropic hyperelasticity and viscoelasticity of elastin.

We are currently studying the structural and functional changes of elastin due to elastin – lipid interactions and glycation. It is well known that elastin is remarkably long lived, and it can suffer from cumulative effects of exposure to chemical damage. End products or side chain modifications from elastin – lipid interactions and glycation compromise the mechanical properties of elastin by altering elastin’s mobility. Changes in the mechanical properties of elastin have important medical and physiological consequences. However the relationship between the molecular level changes and elastin’s mechanical functionality remains unclear. Such knowledge is integral to understanding its performance in living biological systems. The goal of this study is to explore the structural and functional changes of elastin with the combined effects of mechanical and biochemical loadings, thus to advance our understanding of the role of elastin mechanics in vascular remodeling. In collaboration with Dr. Lawrence Ziegler from Chemistry Department, we seek to establish a novel physiologically relevant multi-scale link between structural molecular mobility and tissue mechanical function.