Supplementary Material for: In vivo Imaging of the Cerebral Endothelial Glycocalyx in Mice

Background/Aims: Endothelial glycocalyx refers to the
proteoglycan or glycoprotein layer of vessel walls and has critical
physiological functions. Cerebral glycocalyx may have additional
functions considering the blood-brain barrier and other features.
However, the assessment of it has only been performed ex vivo, which
includes processes presumably damaging the glycocalyx layer. Here we
visualize and characterize the cerebral endothelial glycocalyx in vivo. Methods:
We visualized and quantified the cerebral endothelial glycocalyx in
vivo under a 2-photon microscope by tagging glycocalyx and vessel lumen
with wheat germ agglutinin lectin and dextran, respectively. The radial
intensity was analyzed to measure the thickness of the cerebral
endothelial glycocalyx in each vessel type. Results:
Cerebral arteries and capillaries have an intact endothelial glycocalyx,
but veins and venules do not. The thickness of the glycocalyx layer in
pial arteries, penetrating arteries, and capillaries was different;
however, it was not correlated with the vessel diameter within each
vessel type. Conclusion: We characterized the distribution
of the cerebral endothelial glycocalyx in vivo. Compared to the results
from ex vivo studies, the layer is thicker, indicating that the layer
may be damaged in ex vivo systems. We also observed an inhomogeneous
cerebral endothelial glycocalyx distribution that might reflect the
functional heterogeneity of the vessel type.