The glycocalyx of human, bovine and murine microvascular endothelial cells cultured in vitro.

This study investigated the morphology and thickness of the glycocalyx linings of microvascular endothelial cells (MVEC). Three distinct cell types were used: the human dermal cells (HDMVEC), the murine cardiac cells (MCMVEC) and the bovine luteal cells (BLMVEC). Cells were cultivated for 48 h. Glycocalyx was stained with ruthenium red and examined under a transmission electron microscope. The glycocalyx of HDMVEC was thin and constant (10-22 nm). No glycocalyx was detected within intracellular vesicles. Two cell populations of MCMVEC were recorded. The minor MCMVEC population was well differentiated and covered with heterogenous glycocalyx (2-200 nm). Conglomerates formed above the baseline along the cell extensions. The major MCMVEC population was undifferentiated and coated by a smooth and thin (12-25 nm) layer of glycocalyx. Intracellular vesicles were also coated with glycocalyx. In the BLMVEC population, 10% had 3-170 nm of discontinuous glycocalyx. Rough conglomerates were observed along cell sprouts. Their intracellular vesicles were coated with glycocalyx. The study found vast differences in the morphology and thickness of endothelial glycocalyx among different MVEC under in vitro cultivation. The only record of active endocytosis was in BLMVEC and MCMVEC. No evidence of active endocytosis was found in HDMVEC.