October 2015

We’re back with more exciting updates about current research in Ophthalmology.

We may be one step closer to a cure for age related macular degeneration! Surgeons in London have carried out the first stem cell transplant for AMD as part of an 18 month trial.

Does the new research carried out in dogs hold the key to colour blindness? A study has shown that gene therapy may be the answer.

Look out for more news in the coming months.

Rachel

 

Age-related blindness cure steps closer with new stem cell trial

Surgeons in the UK have successfully transplanted eye cells derived from stem cells behind the retina of a patient with wet age-related macular degeneration. The operation is the first to be performed in the London Project to Cure Blindness, a UK-based collaboration aiming to cure vision loss in patients with this disease.

Age-related macular degeneration (AMD) is a leading cause of vision loss among people aged 50 and older, while macular degeneration in general accounts for nearly half of all visual impairment in the developed world. There are two types of AMD. The most common type is dry AMD, accounting for around 90% of macular degeneration cases. It is caused by the degeneration of the layer of retinal pigment epithelial (RPE) cells in the macula. Less common and more severe is wet AMD, typically caused by abnormal blood vessels leaking fluid or blood into the macula region. Cases of wet AMD usually begin as dry AMD.

The London Project to Cure Blindness is examining whether transplanting RPE cells can be a safe and effective form of treatment for wet AMD. For the trial, RPE cells derived from stem cells are used to replace those damaged by wet AMD via a special patch that is surgically inserted behind the retina.

Prof. Da Cruz carried out the first of these transplants on a patient last month and, so far, no complications have been reported. We will have to wait until Christmas though to know whether the transplant has had any affect upon the patient’s vision. In full, the trial will assess 10 patients with wet AMD over the course of 18 months. After receiving the transplanted RPE cells, each patient will be observed for a year so that the safety and efficacy of the treatment can be monitored

If this new form of treatment is found to be successful, the researchers believe that it could also be used to help patients whose vision is being eroded by the early stages of dry AMD; it may also lead to treatments for other eye conditions too.

References:

“Age-related blindness cure steps closer with new stem cell trial”, Sept 29, 2015, Medical News Today. Retrieved from http://www.medicalnewstoday.com/articles/300201.php. Accessed October 05, 2015

 

Cure for rare form of color blindness steps closer with novel gene insight

Achromatopsia is an inherited disorder that affects around 1 in 30,000 people. The condition is triggered by abnormalities in the retina. People with achromatopsia will experience partial or total loss of color vision, as well as sensitivity to light.

At present, there is no cure for achromatopsia. Current treatments to help manage the condition include the use of red-colored lenses to reduce sensitivity to light and boost visual functioning.

However, ongoing research using animal models has identified gene therapy as a promising avenue for an achromatopsia cure, and this latest study - conducted by researchers from Temple University in Philadelphia, PA, and the University of Pennsylvania - brings the strategy one step closer.

Senior author Karina Guziewicz, of the School of Veterinary Medicine at the University of Pennsylvania, and colleagues began their study by analyzing a German shepherd dog who display classical symptoms of achromotopsia. The researchers set out to identify the genetic cause of the dog's vision loss, though they found none of the known gene mutations that lead to achromatopsia in dogs.

By analyzing five genetic mutations known to play a part in how light signals are sent from the eye to the brain. The team identified a mutation in a gene called CNGA3 that was responsible for the German shepherd's vision loss.

On analyzing Labrador retrievers that had similar symptoms of vision loss to the German shepherd, the researchers identified a different mutation on the same area of the CNGA3 gene where the German shepherd's mutation was found.

The team notes that these mutations have never before been identified in dogs, but the gene mutation found in the German shepherd have been found in humans, highlighting dogs as a valuable model in which to study human achromatopsia.

Next, the team adopted a supercomputer technique that allowed them to identify small changes in protein sequences that may have important implications for visual signaling.

From this, they found that the two mutations found in the CNGA3 gene of dogs impaired the function of the cyclic nucleotide channel, which plays a major role in converting visual signals.

These findings, the researchers say, offer new insights into the molecular mechanisms underlying achromatopsia and emphasize the potential for gene therapy to cure the condition in both dogs and humans.

 

References:

H Whiteman, “Cure for rare form of color blindness steps closer with novel gene insight”, October 05, 2015, Medical News Today. Retrieved from http://www.medicalnewstoday.com/articles/300426.php. Accessed on October 05, 2015