Age-related changes in venous endothelial phenotype at human retinal artery-vein crossing points.

Purpose: To investigate the venous endothelial phenotype at retinal artery-vein (AV) crossings and age-related changes in human cadaveric eyes.
Methods: Eighteen human donor eyes free of known ocular diseases were divided into two groups according to age (≤30 and >50 years). The central retinal artery was cannulated and perfused with oxygenated Ringer's solution with 1% bovine serum albumin. The perfusate solutions were switched to fixative, membrane permeabilizing solution, and selected labeling solutions for microfilament F-actin and nucleic acid in vascular endothelial cells and smooth muscle cells. The eyes were then immersion fixed and the retinas flat mounted. The venous endothelial cells were examined by confocal microscopy at the AV, pre-AV, and post-AV crossing regions.
Results: There was no significant difference between the younger and older groups in endothelial cell length upstream or downstream from an AV crossing. At the AV crossing, the venous endothelial cells were shorter in the younger group and longer in the older group compared with those upstream or downstream from the AV crossing. Stress fibers were not frequently observed in the endothelial cells of younger donors. However, the older group had numerous stress fibers in their endothelia at AV crossing points.
Conclusions: Age-related phenotype changes in venous endothelial cells have been identified in the region of AV crossings providing supportive evidence for the hypothesis of age-related and site-specific changes in the vascular endothelial cells as an important factor contributing to the pathogenesis of branch retinal vein occlusion.