Chemical Helps Blind Mice See Again
Three blind mice? Not anymore.
In a major advance in the field of vision restoration, a team of scientists at the University of California, Berkeley along with researchers at the University of Munich and University of Washington in Seattle have discovered a chemical that temporarily restores some vision to blind mice.
The chemical, called AAQ (acrylamide-azobenzene-quaternary ammonium), acts on the light sensitive cells in the retina - the rods and cones - which are killed in genetic diseases that cause blindness. AAQ binds to protein ion channels on the surface of those dead cells, and when 'switched on' by light, the chemical alters the flow of neurons through the channels, activating the neurons in much the same way as rods and cones are activated by light.
Like Us on Facebook
"This is similar to the way local anesthetics work: they embed themselves in ion channels and stick around for a long time, so that you stay numb for a long time," lead researcher Richard Kramer said. "Our molecule is different in that it's light sensitive, so you can turn it on and off and turn on or off neural activity."
The mice in the experiment had genetic mutations that made their rods and cones die within months of birth, mimicking the cell death of those with the genetic disease retinitis pigmentosa - the most common inherited form of blindness - as well as age-related macular degeneration.
Once injected with AAQ, the mice showed signs of restored vision. It is unclear how well the treated mice could see, but researchers could tell the chemical had an effect because their pupils contracted in bright light and the mice displayed avoidance of light, reports Agence France-Presse.
The chemical eventually wears off, which makes it a safe alternative to other experimental approaches to restoring vision, such as gene or stem cell therapies.
"The advantage of this approach is that it is a simple chemical, which means that you can change the dosage, you can use it in combination with other therapies, or you can discontinue the therapy if you don't like the results. As improved chemicals become available, you could offer them to patients. You can't do that when you surgically implant a chip or after you genetically modify somebody," Kramer said.
The team is working on an improved compound that may someday allow people with degenerative blindness to regain sight.
"We still need to show these compounds are safe and will work in people the way they work in mice but these results demonstrate this class of compound restores light sensitivity to retinas blind from genetic disease," said co-author Russell Van Gelder, according to The Daily Mail.
© 2012 iScience Times All rights reserved. Do not reproduce without permission.