Corporate Banner
Satellite Banner
Genomics
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

Chemical Makes Blind Mice See

Published: Wednesday, August 01, 2012
Last Updated: Wednesday, August 01, 2012
Bookmark and Share
Researchers who discovered the chemical are working on an improved compound that may someday allow people with degenerative blindness to see again.

A team of UW Medicine researchers, in collaboration with scientists at the University of California, Berkeley, and the University of Munich, conducted the study. Their findings appear in the July 26th issue of the journal Neuron.

The approach could eventually help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness, as well as age-related macular degeneration, the most common cause of acquired blindness in the developed world. In both diseases, the light sensitive cells in the retina — the rods and cones — die, leaving the eye without functional photoreceptors.

“This is a major advance in the field of vision restoration,” said co-author Dr. Russell Van Gelder, chair of the Department of Ophthalmology at the UW School of Medicine.

The chemical, called AAQ, acts by making the remaining, normally “blind” cells in the retina sensitive to light, said lead researcher Richard Kramer, UC Berkeley professor of molecular and cell biology. AAQ is a photoswitch that binds to protein ion channels on the surface of retinal cells. When switched on by light, AAQ alters the flow of ions through the channels and activates these neurons much the way rods and cones are activated by light.

“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,” 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.”

Because the chemical eventually wears off, it may offer a safer alternative to other experimental approaches for restoring sight, such as gene or stem cell therapies, which permanently change the retina. It is also less invasive than implanting light-sensitive chips in the eye.

“The photoswitch approach offers real hope to patients with retinal degeneration,” Van Gelder said. “We still need to show that these compounds are safe and will work in people the way they work in mice, but these results demonstrate that this class of compound restores light sensitivity to retinas blind from genetic disease.”

The blind mice in the experiment had genetic mutations that made their rods and cones die within months of birth and inactivated other photopigments in the eye. After injecting very small amounts of AAQ into the eyes of the blind mice, Van Gelder and his colleagues confirmed that they had restored light sensitivity because the mice’s pupils contracted in bright light, and the mice showed light avoidance, a typical rodent behavior impossible without the animals being able to see some light. The team is hoping to conduct more sophisticated vision tests in rodents injected with the next generation of the compound.

“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.

From optogenetics to implanted chips

The current technologies being evaluated for restoring sight to people whose rods and cones have died include injection of stem cells to regenerate the rods and cones; “optogenetics,” that is, gene therapy to insert a photoreceptor gene into blind neurons to make them sensitive to light; and installation of electronic prosthetic devices, such as a small light-sensitive retinal chip with electrodes that stimulate blind neurons. Several dozen people already have retinal implants and have had rudimentary, low vision restored, Kramer said.

Eight years ago, Kramer, Trauner, a former UC Berkeley chemist now at the University of Munich, and their colleagues developed an optogenetic technique to chemically alter potassium ion channels in blind neurons so that a photoswitch could latch on. Potassium channels normally open to turn a cell off, but with the attached photoswitch, they were opened when hit by ultraviolet light and closed when hit by green light, thereby activating and deactivating the neurons.

Subsequently, Trauner synthesized AAQ (acrylamide-azobenzene-quaternary ammonium), a photoswitch that attaches to potassium channels without the need to genetically modify the channel. Tests of this compound are reported in the current Neuron paper.

New versions of AAQ now being tested are better, Kramer said. They activate neurons for days rather than hours using blue-green light of moderate intensity, and these photoswitches naturally deactivate in darkness, so that a second color of light is not needed to switch them off.


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,500+ scientific posters on ePosters
  • More than 3,700+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Genetic Errors Linked To Aging Underlie Leukemia That Develops After Cancer Treatment
New research by Daniel Link, MD, and colleagues at The Genome Institute at Washington University has revealed that mutations that accumulate randomly as a person ages can play a role in a fatal form of leukemia that develops after treatment for another cancer.
Wednesday, December 10, 2014
Genetically Identical Bacteria Can Behave in Radically Different Ways
Although a population of bacteria may be genetically identical, individual bacteria within that population can act in radically different ways.
Friday, January 03, 2014
Depletion of ‘Traitor’ Immune Cells Slows Cancer Growth in Mice
When a person has cancer, some of the cells in his or her body have changed and are growing uncontrollably.
Wednesday, September 25, 2013
Breakthrough in Detecting DNA Mutations Could Help Treat Tuberculosis and Cancer
The slightest variation in a sequence of DNA can have profound effects.
Tuesday, July 30, 2013
Extra Chromosome 21 Removed from Down Syndrome Cell Line
Scientists have succeeded in removing the extra copy of chromosome 21 in cell cultures derived from a person with Down syndrome, a condition in which the body’s cells contain three copies of chromosome 21.
Monday, November 12, 2012
Exome Sequencing of Health Condition Extremes Can Reveal Susceptibility Genes
Comparing the DNA from patients at the best and worst extremes of a health condition can reveal genes for resistance and susceptibility.
Tuesday, July 17, 2012
Gene Therapy Delivered Once to Blood Vessel Wall Protects Against Atherosclerosis in Rabbit Studies By Leila Gray
The results came from research in rabbits, published July 19 in the journal Molecular Therapy.
Tuesday, July 26, 2011
Genetic Region Linked to a Five Times Higher Lung Cancer Risk
A narrow region on chromosome 15 contains genetic variations strongly associated with familial lung cancer, says a study conducted by scientists at Washington University.
Monday, September 22, 2008
Eight new Human Genome Projects Offer Large-Scale Picture of Genetic Differences among Individual
A nationwide consortium led by the University of Washington has completed the first sequence-based map of structural variations in the human genome.
Tuesday, May 06, 2008
Cancer Cells More Likely to Genetically Mutate
Researcher at University of Washington find that the cells who become cancerous can also become 100 times more likely to genetically mutate than regular cells.
Friday, February 23, 2007
Scientific News
Liquid Biopsies: Utilization of Circulating Biomarkers for Minimally Invasive Diagnostics Development
Market Trends in Biofluid-based Liquid Biopsies: Deploying Circulating Biomarkers in the Clinic. Enal Razvi, Ph.D., Managing Director, Select Biosciences, Inc.
Long Telomeres Associated with Increased Lung Cancer Risk
Genetic predisposition for long telomeres predicts increased lung adenocarcinoma risk.
Expanding the Brain
A team of researchers has identified more than 40 new “imprinted” genes, in which either the maternal or paternal copy of a gene is expressed while the other is silenced.
Identifying a Key Growth Factor in Cell Proliferation
Researchers discover that aspartate is a limiter of cell proliferation.
Study Uncovers Target for Preventing Huntington’s Disease
Scientists from Cardiff University believe that a treatment to prevent or delay the symptoms of Huntington’s disease could now be much closer, following a major breakthrough.
The Genetic Roots of Adolescent Scoliosis
Scientists at the RIKEN Center for Integrative Medical Sciences in collaboration with Keio University in Japan have discovered a gene that is linked to susceptibility of Scoliosis.
A Gene-Sequence Swap Using CRISPR to Cure Haemophilia
For the first time chromosomal defects responsible for hemophilia have been corrected in patient-specific iPSCs using CRISPR-Cas9 nucleases
New Tool Uses 'Drug Spillover' to Match Cancer Patients with Treatments
Researchers have developed a new tool that improves the ability to match drugs to disease: the Kinase Addiction Ranker (KAR) predicts what genetics are truly driving the cancer in any population of cells and chooses the best "kinase inhibitor" to silence these dangerous genetic causes of disease.
Understanding the Molecular Origin of Epigenetic Markers
Researchers at IRB Barcelona discover the molecular mechanism that determines how epigenetic markers influence gene expression.
New Tech Enables Epigenomic Analysis with a Mere 100 Cells
A new technology that will dramatically enhance investigations of epigenomes, the machinery that turns on and off genes and a very prominent field of study in diseases such as stem cell differentiation, inflammation and cancer has been developed by researchers at Virginia Tech.
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,700+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!