Human dermal pericytes express 3G5 ganglioside - A new approach for microvessel histology in the skin

Background: Pericytes cover the abluminal surface of microvessels and play an important role in capillary regulation and pathology. Studies on pericytes have been hindered by the lack of specific markers with which to facilitate microscopic identification of this cell type Expression of the cell surface 3G5 ganglioside antigen has been reported in cultured retinal and cardiac pericytes. The objective of this study was to determine the usefulness of monoclonal antibody 3G5 as a pericyte marker in human skin. Methods: Cryosections of 21 skin biopsies were examined by direct fluorescence technique with anti-3G5, anti-von Willebrand factor, anti-alpha -smooth muscle actin or DNA fluorochrome. Results: In human dermis, 3G5 expression is limited to pericytes discriminating this cell type from all other cells including smooth muscle cells, myofibroblasts and myoepithelial cells. We found a pericyte: endothelial cell ratio of 1:12.4 (+/-7.1), and a difference of a smooth muscle actin expression between the subpapillary plexus and the microvessels of the Stratum reticulare. Conclusions: 3G5 mAB is an excellent and so far the only reported tool for identification of dermal pericytes by fluorescent light microscopy. Moreover, this is the first report of the application of 3G5 technique to the microvasculature in tissue sections at the light microscopic level.