Zebrafish study confirms regenerated photoreceptor cells fully restore vision

Key Takeaways

• Researchers have found that regenerated photoreceptor cells in zebrafish regain their original function, allowing the fish to recover complete vision.
• The results offer promising insights for the future of photoreceptor replacement therapies.

Vision is a complex sense that depends on the retina, a neural tissue in the back of our eyes. The retina is where photoreceptor cells capture light and convert it into electrical signals, which are then sent to the brain and processed as vision.

Some blinding diseases lead to permanent vision loss by irreversibly damaging photoreceptor cells, which humans cannot naturally regenerate. Although researchers are working on methods to regenerate these cells, the crucial question is whether these regenerated photoreceptors can fully restore vision.

Unlike humans, zebrafish have the remarkable ability to regenerate parts of their nervous system even after severe damage. Zebrafish can regrow photoreceptors from special stem cells located in the retina, known as Müller glia. This unique ability makes zebrafish an ideal model for studying the potential to restore vision through photoreceptor regeneration.

Various researchers – including the group of Prof. Brand Michael Brand at the Center for Regenerative Therapies Dresden (CRTD) of Dresden University of Technology – have developed behavioral tests that confirmed that zebrafish regain vision after photoreceptor regeneration. However, these tests could not directly assess the extent to which the photoreceptor function was restored. “The only comprehensive test to see if the vision is fully restored is to directly measure the electrophysiological activity of the retinal cells. Are photoreceptors correctly stimulated by the various colors of light? Are they electrically active to the same extent?” says Prof. Brand.

To answer these questions, the Brand team used a genetically modified zebrafish that let them use high-end microscopy to track the activity of photoreceptors. They found that the regenerated photoreceptors responded to light at different wavelengths, transmitted the electric signal to neighboring cells, and did so with the same sensitivity, quality, and speed as original photoreceptors in an intact retina. Their results were published in the journal Developmental Cell.

“It is important to note that, at this stage, our work is classical basic research. It is still a long way until it can be applied in the clinic. However, being able to eventually achieve such functional regeneration from stem cells already located in the human retina could potentially revolutionize the treatment of currently untreatable diseases like retinitis pigmentosa or macular degeneration. This study brings us one step closer to that dream,” concludes Prof. Brand.

Edited by Suditi Kedambadi and Miriam Kaplan, PhD.

Source:

Magdalena Gonciarz, Dresden University of Technology, Medical Xpress, August 27, 2024; see source article