Role of heparan sulfate and hyaluronan in mechanical properties of the lung microvascular glycocalyx

An intact lung capillary glycocalyx is vital to normal vascular barrier function and subsequently normal pulmonary function. Evidence suggests that the glycocalyx provides active regulatory functions, which are fundamental to normal lung fluid balance and that endothelial surface glycoproteins participate in agonist-mediated signaling. Heparan sulfates and hyaluronan glycosaminoglycans are of particular interest in mechanostimulation and subsequent mechanotransduction because of direct and indirect attachment to intracellular components involved with barrier maintenance. Also important to glycocalyx structure are associated blood serum proteins. The component contribution to the overall glycocalyx mechanical environment is integral to its transfer of extracellular mechanical signals to intracellular signals.;These components have not been characterized in terms of their mechanical contribution to the glycocalyx stiffness, which allows for endothelial mechanotransduction. Understanding these components will assist in developing a strategy to treat acute inflammation of the lungs.;In this dissertation, the mechanical contributions of glycosaminoglycans (heparan sulfate and hyaluronan) and associated macromolecules (albumin and hydroxyethyl starch) to lung glycocalyx mechanical structure are measured with novel applications of two optical micromechanical techniques: atomic force microscopy and reflectance interference contrast microscopy. This information is combined into an inclusive mechanical model. Specifically, the biomechanical properties of the microvascular glycocalyx were acquired and analyzed by probing with physiologically relevant normal forces. The techniques and experiments described in this dissertation provided means to measure and potentially other soft biologic materials, including the local glycocalyx microenvironment.