Glycocalyx damage estimated using colloidal iron staining.

Anionic constituents in the peritubular capillary basement membranes and the glomerular endothelial cells have been demonstrated to function as a size- and charge-selective barrier. Cationic colloidal iron staining of human biopsy specimens revealed a glycocalyx on the surface of the glomerular basement membrane (GBM), peritubular capillary (PTC) endothelial cells, and brush border of the tubular epithelial cells of normal kidney. However, the glycocalyx was abolished in the PTC wall of C4d-positive acute humoral rejected kidney, and in the GBM as well as the PTC wall of a chronic, allograft, nephropathy kidney. In addition, cyclosporine eliminated the glycocalyx in the PTC wall, while treatment with heparin inhibited the elimination of the PTC glycocalyx. In conclusion, the glycocalyx on the surface of the GBM and PTC is an important component in the endothelial cell barrier.