Immunolocalization of endocan during the endothelial-mesenchymal transition process

Endocan is a dermatan sulfate proteoglycan (DSPG) that has been observed in the cytoplasm of endothelial cells of small and large vessels in lung, kidney, liver, colon, ovary and brain tumors. This DSPG has been implicated in the regulation of cellular activities such as adhesion, migration, and proliferation. Given the important roles played by endocan in such processes, we sought to determine whether this DSPG is present in the chicken embryo aortic wall in embryonic days 12 and 14 when intimal thickening and endothelial transformation are notorious. Immunolabeling of serial paraffin cross-sections revealed endocan immunoreactivity at the endothelium and some mesenchymal cells constituting the intimal thickening but not in the cells arranged in lamellar layers. We also investigated whether endocan was present in monolayers of primary embryonic aortic endothelial cells attached to fibronectin and stimulated with epidermal growth factor. Endocan immunoreactivity was detected at the plasma membrane in arrays typical of focal complexes in the leading edge of the cells that were separating, detaching, and migrating toward cell-free areas. This study demonstrates for the first time the presence of endocan during the aortic wall remodeling, and provides evidence that suggests a possible contribution of this DSPG in the EndoMT process.