Endothelial glycocalyx glycan expression in lymphatic vasculature in mice.

Lymphatic vessels are crucial for the drainage and transport of interstitial fluids, cells, and macromolecules. Like all other cells, lymphatic endothelial cells express a cell-surface glycocalyx, composed of carbohydrate-enriched molecules, that contributes to endothelial barrier maintenance and cell-cell communication. Although the endothelial glycocalyx has been increasingly studied in blood endothelium, little has been done to characterize it in lymphatics. In this study, among a variety of tested fixatives, Carnoy's fixative, a solution of ethanol, chloroform, and acetic acid, was determined to best preserve endothelial glycocalyx epitopes in lymphatics-on-chip microfluidic devices and mouse tissue sections. Dermal, lung, and lymph node tissues were isolated from male C57BL/6J mice and fixed with Carnoy's fixative. We aimed to determine the presence of prominent glycocalyx components, including heparan sulfate and chondroitin sulfate, across different mouse organs to characterize organ-specific differences. We hypothesized that, due to the different organ environment demands for fluid clearance and immune surveillance, the expression of major glycocalyx components would be heterogeneous. However, immunofluorescence imaging of these tissues demonstrated the presence of these glycans within LYVE-1-positive structures across the tested tissues. This conclusion provides a basis for further characterization and understanding of the composition, function, and potential alterations of the lymphatic endothelial glycocalyx across very distinct organs/tissues and conditions.