Age-related macular degeneration affects 11 million people in the U.S., and that number is expected to nearly double by 2050.
Now researchers are looking into how a unique characteristic of a zebrafish can regenerate retinas in humans and keep people seeing as they age.
These fish might be tiny, but they come with some supersized powers.
"Zebrafish, unlike mammals, are able to regenerate parts of their retina if they become injured," Vanderbilt Vision Research Center director Dr. David Calkins said.
That is why researchers from Vanderbilt University Medical Center are studying how this characteristic of zebrafish can help humans dealing with age-related vision loss due to damage to the retina.
"The cells that make up the retina between the fish and the human eye are very, very similar," Vanderbilt professor of biological sciences Dr. James Patton said.
The exception is one cell called MG for Muller glia. In a zebrafish, when that cell is damaged, it will activate and then regenerate.
"So, the fish will go from blind to about 2 1/2 weeks later, total regain of eyesight," Patton said.
Humans have the same Muller glia cell but are incapable of regeneration like the zebrafish. But Patton is trying to find out if suppressing a certain type of micro RNA in humans could activate Muller glia the same way it does in zebrafish.
Currently, the economic burden for eye disorders and vision loss sits at $139 million.
"If there were ways to keep people seeing and overcome degenerative disorders, that would have a huge economic impact, not to mention quality of life," Patton said.
Interestingly, the zebrafish is used often to study human traits and diseases because they share 70% of humans' genetic code.
Before human testing, they will have to test on smaller mammals, such as mice, and see if they can suppress a particular mirco-RNA that regulates the Muller glia cell.
TOPIC: AMAZING ZEBRAFISH CURE BLINDNESS: MEDICINE'S NEXT BIG THING?
REPORT: MB #4699
BACKGROUND: Wet macular degeneration is a constantly occurring eye disorder that causes blurred vision or a blind spot in your field of vision. Causes are abnormal blood vessels that leak fluid or blood into the macula. The macula is in the part of the retina responsible for central vision. There are two types of age-related macular degeneration: Wet macular degeneration and dry macular degeneration. The latter is more common and less severe. The wet type always begins as the dry type. Symptoms appear suddenly and worsen rapidly. They can include visual distortions, reduced central vision, very bright colors, blurry and blind spots in vision, and general haziness. Visit a doctor if you notice changes in central vision and colors are impaired. (Source: https://www.mayoclinic.org/diseases-conditions/wet-macular-degeneration/symptoms-causes/syc-20351107 )
DIAGNOSING: After reviewing family and medical history, doctors complete an eye exam of the back of the eye. They apply special drops to view the back part and look for drusen, which appear as multiple yellow spots under the retina. Doctors also use an Amsler Grid to check if the patient is seeing straight lines or if they are broken, faded, or distorted. The latter is defects in central vision. During a fluorescein angiography test, colored dye is injected into an arm vein that travels to and highlights the blood vessels of the eye. A special camera takes pictures as the dye travels through the blood vessels and detects if abnormal blood vessels are leaking. (Source: https://www.mayoclinic.org/diseases-conditions/wet-macular-degeneration/diagnosis-treatment/drc-20351113 )
NEW TECHNOLOGY: There is a treatment where stem cells are injected into the back of the eye to see if those stem cells will integrate into the retina and then replace lost cell types. A stem cell that's already a resident cell in the retina is used to replace all the rest of the lost cells This is similar to the method that the muller glia cell naturally does in the zebrafish. However, humans have the same muller glia cell with a similar structural makeup, yet the reparations do not naturally occur like they do in the zebrafish. Scientists have found the micro RNA processing enzyme, dicer, acts as a gatekeeper for the muller glia cell. This is the part that differentiates the zebrafishes' ability to restore vision on its own when a human cannot. (Source: https://www.cell.com/cell-reports/fulltext/S2211-1247(19)30965-9 )