Transmission electron microscopy demonstration of reduced endothelial glycocalyx in severe preeclampsia

Endothelial glycocalyx is a carbohydrate-rich layer lining the luminal side of blood vessels. Its damage was demonstrated in different groups of critically ill patients. Indirect evidence showed that endothelial glycocalyx degradation might be an important factor in pathophysiology of preeclampsia. The aim of our study was to demonstrate endothelial glycocalyx by transmission electron microscopy and to compare its amount in the omentum vessels of pregnant patients with severe preeclampsia and two control groups.

Patients with severe preeclampsia who had a cesarean section were included in the study. Controls were healthy pregnant people at term with an elective cesarean section and non-pregnant patients of reproductive age who underwent laparoscopy for benign conditions. We performed omentum biopsies in all three groups. Samples were prepared for transmission electron microscopy using perfusion with ruthenium red. We measured the amount of endothelial glycocalyx attached to apical plasma membrane of endothelial cells as the area of glycocalyx observed with transmission electron microscope.

In the analysis we included nine patients from each group and demonstrated statistically significant difference in the amount of endothelial glycocalyx among the three groups (p = 0.018). Glycocalyx was significantly reduced in severe preeclampsia (median 1.90 μm², interquartile range 0.80-4.1 μm²) compared to non-pregnant controls (median 14.34 μm², interquartile range 3.80-73.32 μm²⁾; p = 0.021. A trend towards reduced glycocalyx amount in preeclampsia vs. pregnant controls and pregnant controls vs. non-pregnant controls was observed but without statistical significance.

Compared to non-pregnant controls the endothelial glycocalyx was significantly reduced in pregnant patients with severe preeclampsia.