The impossible possibility of regrowing photoreceptors

One day rebuilding an eye’s damaged photoreceptor layer could be as easy as regrowing a fingernail, if current research in dogs lives up to its promise.

University of Pennsylvania researchers shattered optical dogma several years ago when they found – contrary to common belief that photoreceptors never regenerated – retinal cells in young canines do actually undergo cellular division.

This regeneration of photoreceptors – some functional – occurs in dogs with degenerative retinal diseases, before the overwhelming cell death rates that cost the animals their sight.

The continued study has now shown this regrowth, indicated by biomarkers left in cells after they divide, happening in cases of other degenerative sight diseases including X-linked progressive retinal atrophy.

The important next step is to determine the genes that switch photoreceptor division on and off.

From there may come a therapy that could utilise this process to save an animal or person’s sight, Pennsylvania School of Veterinary Medicine Professor Gustavo Aguirre told OT.

“You could now have a dual approach to treatment for some diseases. You could slow the rate of cell death while allowing the cells to divide, [which] is much more effective,” he highlighted.

It is likely similar cellular division happened in human, as well as canine, photoreceptors, Professor Aguirre emphasised.

“This will have broad application across mammal species with few exceptions,” he said.

Excitingly, it appears, in some cases, the set of cells that are dividing are distinctly different from the ones that are dying.

Fellow researcher, Kristin Gardiner, explained: “We wanted to make sure that these weren’t some aberrant cells that were expressing all these different markers.”