Received: 4 October 2006 / Accepted: 9 January 2007 / Published online: 26 January 2007 | Sietze Reitsma · Dick W. Slaaf · Hans Vink · Marc A. M. J. van Zandvoort · Mirjam G. A. oude Egbrink
This review provides an overview of the endothelial glycocalyx, a network of membrane-bound proteoglycans and glycoproteins covering the endothelium. The glycocalyx plays a crucial role in vascular physiology and pathology, including mechanotransduction, hemostasis, signaling, and blood cell-vessel wall interactions. Recent studies have also highlighted its involvement in diabetes, ischemia/reperfusion, and atherosclerosis. The glycocalyx's thickness varies with vascular diameter, and its composition includes heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, and hyaluronic acid. Proteoglycans serve as the backbone, while glycoproteins facilitate cell adhesion and signaling. Soluble components derived from the endothelium or bloodstream contribute to the glycocalyx's functional importance. The glycocalyx acts as a barrier, regulating vascular permeability and influencing blood cell interactions with the vessel wall. It also plays a role in mechanotransduction, mediating shear stress sensing and NO production. Additionally, the glycocalyx controls the microenvironment by binding plasma-derived molecules and anticoagulant mediators. In pathophysiological conditions, such as diabetes, ischemia/reperfusion, and atherosclerosis, the glycocalyx can be disrupted, leading to endothelial dysfunction and increased vascular permeability. Direct visualization techniques, including electron microscopy, intravital microscopy, and two-photon microscopy, have been developed to study the glycocalyx, but challenges remain in accurately measuring its dimensions and composition.This review provides an overview of the endothelial glycocalyx, a network of membrane-bound proteoglycans and glycoproteins covering the endothelium. The glycocalyx plays a crucial role in vascular physiology and pathology, including mechanotransduction, hemostasis, signaling, and blood cell-vessel wall interactions. Recent studies have also highlighted its involvement in diabetes, ischemia/reperfusion, and atherosclerosis. The glycocalyx's thickness varies with vascular diameter, and its composition includes heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, and hyaluronic acid. Proteoglycans serve as the backbone, while glycoproteins facilitate cell adhesion and signaling. Soluble components derived from the endothelium or bloodstream contribute to the glycocalyx's functional importance. The glycocalyx acts as a barrier, regulating vascular permeability and influencing blood cell interactions with the vessel wall. It also plays a role in mechanotransduction, mediating shear stress sensing and NO production. Additionally, the glycocalyx controls the microenvironment by binding plasma-derived molecules and anticoagulant mediators. In pathophysiological conditions, such as diabetes, ischemia/reperfusion, and atherosclerosis, the glycocalyx can be disrupted, leading to endothelial dysfunction and increased vascular permeability. Direct visualization techniques, including electron microscopy, intravital microscopy, and two-photon microscopy, have been developed to study the glycocalyx, but challenges remain in accurately measuring its dimensions and composition.