Figure 1. Quantification of endothelial cell injury and death by propidium iodide staining. Dead and injured retinal endothelial cells were labeled in vivo using propidium iodide. Endothelial cell damage was increased in diabetic animals in capillaries (A), venules (B), and arteries (C). Administration of the TNF-α inhibitor etanercept reduced diabetes-induced endothelial cell injury in all vessel types.