The list of cell types in the retina has a new entry.
David Calkins, PhD, director of the Vanderbilt Vision Research Center, and colleagues recently reported the discovery of a novel population of astrocytes in the mouse retina, the light-sensitive layer of tissue in the eye that receives images and transmits them to the brain. Astrocytes are a type of glial cell that support and help maintain the function of nerve cells in the retina and central nervous system.
The researchers developed a mouse model to fluorescently label cells — in greater detail than previously possible — that express a protein found in astrocytes. They used this tool to explore whether astrocytes in the mouse retina have distinct morphological and electrophysiological features.
In a report in the journal Glia, the team, which included lead author Joseph Holden and collaborator Lauren Wareham, PhD, demonstrated that the novel astrocytes are found in the inner plexiform and ganglion cell layers of the retina and express a set of proteins that define astrocytes.
The novel astrocytes have a different distribution across the eye compared to other retinal astrocytes and are more heavily concentrated near the optic nerve head. Their morphology is also distinct from other retinal astrocytes and glial cells: They resemble interneurons called amacrine cells but do not express neuronal proteins and do not exhibit action potentials (electrical activity characteristic of neurons).
The researchers call the cells “displaced retinal astrocytes” because they are similar to, but removed from, other astrocytes in the retinal nerve fiber layer.
A full understanding of retinal cell types and their functions could point to novel therapeutic targets for diseases that affect the visual system, such as glaucoma — a leading cause of blindness for people over age 60.
Glia featured an image from the Calkins team on the journal cover.
Calkins holds the Denis M. O’Day, MBBS, Chair in Ophthalmology and Visual Sciences and is also Vice President for Research at VUMC, and vice chair and director for Research at the Vanderbilt Eye Institute. The research was supported by the National Institutes of Health (grants P30EY008126, U24EY029903, P30CA068485, P30DK020593, P30DK058404, U2CDK059637), Research to Prevent Blindness, and the Potocsnak Family Vision Research Center.
