Functional differences between sinusoidal endothelial cells and interlobular or central vein endothelium in rat liver

Area of Science:

• Hepatology
• Cell Biology
• Microcirculation

Background:

• The liver's microvasculature comprises sinusoids and central/interlobular veins.
• Endothelial cells lining these structures exhibit specialized functions.
• Understanding the interface between sinus-lining endothelial cells (SLE) and vessel-lining endothelial cells (VLE) is crucial for liver physiology.

Purpose of the Study:

• To investigate the topological relationship between rat liver SLE and VLE.
• To compare the morphological and functional properties of SLE and VLE.
• To elucidate the nature of cell-cell interactions at the sinusoid-vein junction.

Main Methods:

• Intravenous injection of horseradish peroxidase-conjugated denatured albumin (HRP-FDA).
• Liver perfusion and fixation followed by electron microscopy.
• Ultrastructural analysis of endothelial cell morphology and HRP-FDA localization.

Main Results:

• HRP-FDA was found in endocytotic vesicles of SLE and Kupffer cells, but not VLE.
• SLE cells exhibited attenuated cytoplasmic extensions containing HRP-FDA vesicles.
• At the sinusoid-vein junction, SLE and VLE formed direct contacts mediated by overlapping junctions.

Conclusions:

• SLE and VLE in rat liver occupy distinct cellular compartments.
• A direct connection exists between SLE and VLE at the transitional zones of the liver vasculature.
• Overlapping junctions mediate the interaction between these distinct endothelial cell types.