Special Simbios Seminar by Jay Humphrey, Texas A&M University, November 20, 2007

Title: Vascular Adaptation and Mechanical Homeostasis Across Scales

J.D. Humphrey, Ph.D. Regents Professor Department of Biomedical Engineering Texas A&M University, College Station

Blood vessels exhibit a remarkable ability to adapt throughout life, one that depends upon genetic programming and well orchestrated biochemical processes. Findings over the past four decades demonstrate, however, that the mechanical environment experienced by these vessels similarly plays a critical role in governing their adaptive responses. For example, arteries respond to altered blood flow, blood pressure, and axial extension, disease processes such as cerebral aneurysms and vasospasm, and even diverse clinical treatments so as to maintain constant a preferred (homeostatic) mechanical state. Indeed, experiments on isolated microvessels, cell-seeded collagen gels, and adherent cells isolated in culture suggest that vascular cells and sub-cellular structures such as stress fibers and focal adhesions likewise seek to maintain constant a preferred mechanical state. Although much is known about mechanical homeostasis in the vasculature, there remains a pressing need for an integrative mathematical theory that describes and eventually can predict vascular adaptations in response to diverse stimuli. The goal of this presentation is to review the available data on vascular mechanical homeostasis and to discuss a new (constrained mixture theory) approach for modeling.