Fish stem cells may restore human vision

Zebrafish, often used in genetics studies, may hold the key to repairing damaged retinas and returning eyesight to people, Canadian researchers say.

University of Alberta researchers discovered that a zebrafish’s stem cells can selectively regenerate damaged photoreceptor cells.

According to lead researcher Ted Allison, geneticists have known for some time that stem cells in zebrafish - unlike those in humans - can replace damaged cells involved in many components of eyesight.

Rods and cones are the most important photoreceptors. In humans, rods provide us with night vision and cones give us a full-colour look at the world during the day. What was not known, says Allison, was whether the zebrafish stem cells could be instructed to replace only the cones in its retina. This could have important implications for human eyesight.

“This is the first time in an animal research model that stem cells have only repaired damaged cones,” Allison said in a statement.

“For people with damaged eyesight, repairing the cones is most important because it would restore daytime colour vision,” he said. The researchers say that to date, almost all success in regenerating photoreceptor cells has been limited to rods, not cones. Most of these previous experiments were conducted on nocturnal rodents, animals that require good night vision and consequently have far more rods than cones.

“This shows us that when cones die in a cone-rich retina, it is primarily cones that regenerate. This suggests the tissue environment provides cues to instruct stem cells how to react,” said Allison.

The researchers say this shows hope for stem-cell therapy that could regenerate damaged cones in people, especially in the cone-rich regions of the retina that provide daytime colour vision.

“The next step for our team is to identify the particular zebrafish gene that activates repair of damaged cones,” said Allison. The study was published in the journal PLOS ONE.