Zebrafish may lead to blindness treatment

Canadian research offers hope for treatment

An small fish common in pet stores could make a big splash in efforts to restore human eyesight, according to new research from the University of Alberta.

Assistant professor Ted Allison and his team used stem cells that naturally exist in the tiny zebrafish to rebuild damaged, light- sensitive cells called cones inside the fish’s eyes.

Eventually, that science could lead to new treatments for degenerative eye diseases that cause vision loss and blindness in humans, such as macular degeneration and retinitis pigmentosa.

“We think that there’s more hope than we did before to use stem cells to replace cones in the (human) retina, and cones are important for daytime vision,” Allison said in an interview Friday from his office in the U of A’s department of biological sciences.

“The big finding is that it can happen.”

Stem-cell therapy has al- ready been used in mice to regenerate photoreceptors known as rods, responsible for black-and-white vision, Allison said.

However, scientists have not previously regenerated cones, and cones are much more important to human eyesight because they control daytime and colour vision as well as visual acuity, or the ability to see fine details, he said.

“Specific efforts to make cones instead of rods haven’t been working too well,” Allison said.

“If we want to repair things (in people), it’s the cones we want to repair. Repairing rods would be good, because that would repair someone’s nighttime vision ... but if you want to repair vision, you want to return people to operating well in the day. A blind person wants to see in colour and see with good acuity during the day.”

This doesn’t mean scientists will implant zebrafish stem cells in people to fix their vision, Allison said. It does mean human stem cells from a healthy eye could someday be isolated and then transplanted into a damaged human eye to repair cones and restore sight.

Another possibility is that scientists will figure out which genetic “switches” in the zebrafish direct its stem cells to become cone photoreceptors, Allison said. Those findings might help scientists turn those same genes on and off in human stem cells, he said.

ED KAISER/EDMONTON JOURNAL Ted Allison, assistant professor department of biology at the University of Alberta, looks at zebrafish that his research team says may hold the key to restoring daytime, colour vision to human victims of degenerative eye diseases.