5.3 Retinal Cell Types that Produce VEGF

Summary

The retina contains two types of glial cells: macroglia and microglia. The Müller cell is the most common macroglial cell type and is unique to the retina. Shaped like a spindle, Müller cells expand across the entire retina. Müeller cells are thought to have a key role in the pathogenesis of retinal microangiopathy in the diabetic eye because they produce factors that regulate blood flow, cell survival, and vascular permeability, and their processes surround all blood vessels in the retina. The astrocyte is the less common type of macroglial cell. As it develops, the astrocyte travels along the optic nerve to reach the retina. Astrocytes form a monolayer at the inner limiting membrane. In vivo laboratory data have shown that astrocyte connexin-26 and -43 gene and protein expression decreases after 4 weeks of experimentally-induced diabetes and before significant astrocyte loss. During this same time period the retina became hypoxic. These data suggest astrocytes could play a key role in changes in retinal vasculature and inner retinal dysfunction in diabetes.