Endothelial Glycocalyx of Blood Circulation System. I. Detection, Components, and Structural Organization

摘要

The luminal surface of a blood vessel accommodates a complex multicomponent system of mainly carbohydrates and proteins called glycocalyx. According to the concept of the double protective layer, glyco- calyx is the first protection barrier of the vascular wall. The structure of glycocalyx is determined by a group of proteoglycans, glycoproteins, and glycosaminoglycans. Two groups of molecules are distinguished within the glycocalyx constituents, that is, membrane proteoglycans (syndecans and glypicans bound to endothelial cell membranes) and soluble proteoglycans (perlecan, biglycan, versican, decorin, and mimecan). There are five types of glycosaminoglycan chains; these are heperan sulfate, chondroitin sulfate, dermatan sulfate, kera- tan sulfate, and hyaluronan. There is a dynamic equilibrium between the soluble components of glycocalyx and flowing blood, which allows for separation of the endothelial surface layer. Due to its complexity and location at the interface of blood circulation system, glycocalyx is involved in the maintenance of vascular homeostasis. Here, the molecular composition of glycocalyx, properties of its components, biosynthesis, and common structural features are discussed.