MAY 15, 2018 11:33 PM PDT

Genomic Surgery to Treat Eye Disease

WRITTEN BY: Carmen Leitch

CRISPR is a powerful technique that can make permanent edits to the genome, and scientists are trying to perfect it for use in the clinic to treat patients. Errors in the genetic code can cause serious diseases, which might be repaired instead of trying to ease symptoms. Now researchers have used CRISPR to treat damage in mice that model retinitis pigmentosa, a degenerative disorder of the eye, by repairing the genetic mutation. The method, which replaced a dysfunctional gene with a normal one, has been reported in the journal Ophthalmology.

Image credit: Pixabay

CRISPR can act as a kind of scissor that cuts the genome, and because cells will act to repair such cuts, a template containing the correct gene can be added to cells along with the CRISPR reagents. The cell machinery can then use the right gene as a template when it fixes the cut portion of the genome. Researcher Stephen H. Tsang, M.D., Ph.D., and his colleagues think of the method as a kind of genomic surgery. Tsang believes they will be able to test their technique on patients within three years.

"Genome surgery is coming," said Dr. Tsang. "Ophthalmology will be the first to see genome surgery before the rest of medicine."

In people with retinitis pigmentosa, cells in their retinas breakdown and are lost. The disease affects about one of 4,000 people. Usually beginning in childhood, night and peripheral vision are impacted at first. As it progresses into adulthood, it will usually cause blindness in patients by the time they turn 40.

In the autosomal dominant form of the disorder, a person inherits one bad copy of the rhodopsin gene from one parent and usually gets a good copy from the other parent. That means that a treatment must selectively target the bad copy. In autosomal recessive cases, two bad copies, one from each parent, have to be inherited to cause the disease.

Tsang’s team focused on correcting the detrimental copy in a strategy to ‘ablate and replace’ which can fix any number of different mutations, instead of focusing on only one. Over 150 different rhodopsin gene mutations can cause the disease, making this tool especially useful.

 While the CRISPR tool usually targets one small region of the genome, the team’s design targeted two areas of the rhodopsin gene instead. That increased their ability to disrupt it, from 30 to 90 percent. A viral vector was used to deliver the good replacement copy of the gene to the retina for incorporation into the cells there.

The researchers were also able to use their method to correct sequences in cells that were not dividing, an important feature for therapeutic use.

After testing it on their mouse model, the scientists found that the retinal function improved, and degeneration of the retina was slowed.

The video above from Nature describes and animates some of the many different techniques that are made possible by CRISPR.

 

Sources: AAAS/Eurekalert! Via American Academy of Ophthalmology, Ophthalmology

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
NOV 14, 2018
Videos
NOV 14, 2018
The Sunscreen Gene
Wouldn't it be convenient if we didn't have to worry about sunscreen because our bodies were able to just make it when we needed it?...
NOV 27, 2018
Immunology
NOV 27, 2018
A Mutated Immunity
Researchers utilize blood samples to determine cancer neoantigens to create effective vaccination in mouse model...
DEC 03, 2018
Genetics & Genomics
DEC 03, 2018
Reducing the Potential for Negative Side Effects in CRISPR
CRISPR-Cas9 is an amazing gene-editing tool, but there are some drawbacks. This work aims to fix that....
DEC 09, 2018
Health & Medicine
DEC 09, 2018
Health Beliefs That Influence Skin Cancer
  In the U.S., there are over 3.5 million cases of skin cancer reported every year. Basal cell carcinoma and squamous cell carcinoma are the most comm...
JAN 05, 2019
Cell & Molecular Biology
JAN 05, 2019
The Body's Largest Cellular Receptor is Identified
The structure of a huge receptor in the body, which binds to vitamin B12, has now been elucidated....
JAN 09, 2019
Cell & Molecular Biology
JAN 09, 2019
New Findings on the Early Stages of Autism Spectrum Disorder
While the prevalence of autism spectrum disorder has grown, there is still a lot we don't know about what causes the disorder....
Loading Comments...