A Morphological Basis for Microvascular Endothelial Injury Associated with Septic Organs

Abstract

The sugar-protein glycocalyx is known to coat the healthy endothelium, but its ultrastructure has not been well described. Scanning electron microscopy revealed that the endothelial glycocalyx layer in continuous and fenestrated capillaries was substantially thicker than that in the sinusoids. The endothelial glycocalyx in the heart and lungs presented itself as a broccoli- or moss-like structure and covered the entire luminal endothelial cell surface. In the kidney, it nearly occluded the endothelial pores of the fenestrated capillaries and was also present on the surface of the renal podocytes. In the liver sinusoids, it appeared very thin and did not occlude the pores. In a mouse lipopolysaccharide-induced experimental endotoxemia model, the endothelial glycocalyx of the capillaries was found to be severely disrupted；that is, it appeared to be peeling off the cells and forming clumps. The latter may provide a morphological basis for the microvascular endothelial dysfunction associated with septic injury of the organs.