Advances in the battle against blindness

Last year, a gene therapy treatment restored some vision in children with congenital blindness. The Foundation Fighting Blindness says more innovations are coming.
Written by Christina Hernandez Sherwood, Contributing Writer

Bringing hope to people facing congenital blindness, researchers announced last year a gene therapy treatment that restored some vision in children with the condition. The treatment was the first of many funded by the Foundation Fighting Blindness, whose mission since the 1970s has been to find prevention, treatments and cures for rare retinal diseases that cause blindness.

I spoke last week with Dr. Stephen Rose, the foundation's chief research officer, about the groundbreaking gene therapy study -- and about forthcoming innovations in fighting blindness.

Talk about what the gene therapy study entailed.

The study is a gene therapy for a rare form of retinal-cause blindness called Leber's congenital amaurosis (LCA). The back of the eye from birth or shortly thereafter stops working correctly due to the fact that a molecule in the cells that turns light into electricity is not working correctly. Through research, it was determined that the lack of this molecule doesn't kill the cells immediately. It turns them off and with time, they die. The feeling is that if we can put this molecule back into those cells early enough, we can turn those cells back on again.

In pre-clinical studies using animals with the same form of LCA [it was proven] that if you turned back on those cells by supplying the missing molecule, vision is restored. That's what the clinical trial did. The foundation started funding the exact research on this form of LCA in the early '90s all the way through the pre-clinical studies and the clinical trial. The group at Children's Hospital of Philadelphia, as well as two other groups doing the trials at the same time, took individuals who were essentially blind from childhood and delivered a good copy of the missing gene into the back of the eye. It was taken up by the cells and those cells started producing the missing molecule. Certain amounts of vision were restored.

The case talked about most is this child of 8 years old who received the treatment. This individual, prior to receiving the treatment, was not totally blind but was so severely vision-impaired that he had to sit at the back of the classroom with a big LCD screen to see the blackboard. [After the treatment] he could see many more lines on an eye chart than he could ever see before. He went from having to sit at the back of a classroom with a big LCD screen to sitting in the front of the classroom and seeing the chalkboard without assistance. He finished his first season of playing softball. It did not restore 100 percent vision and it was only treatment in one eye, but it was a tremendous advance.

What's being done now is: Can we do the second eye? Can we do two eyes together? Then [can we] bring it down into children of a younger age? The older people are who are affected by this, the more issues there are with more of those cells at the back of the retina dying. The plan is to take this down to individuals who are as young as two years old and to where individuals can be treated very early in life so they will have lost essentially no vision.

Will this therapy work for people with other types of vision loss?

This particular gene therapy is for these particular individuals. But we are working with investigators to bring this same technology to other forms of congenital blindness, such as Stargardt's diseasewhich is the juvenile form of  age-related macular degeneration. We're working with investigators and bio-tech companies to start a clinical trial by the end of 2010. There's another form, the largest form of deaf-blindness in the world, calledUsher syndrome. The hair cells in the ear and these cells that perceive light in the eye share a number of molecules. One of them leads to deaf-blindness. We're looking at doing gene therapy for the blindness part of this starting in 2011. Not all forms of retinal degeneration are going to be amenable to gene therapy. There are over 200 genes mapped so far that are linked to these retinal degenerations and we know there are many more.

We're also working on stem cells. Certainly the Holy Grail would be to rebuild the retina for people who have gone blind. That's years off, but we're making progress. We have investigators who [can] take stem cells through a pathway to turn into these specific retina cells and have implanted them in animals and have shown restoration of vision. We now need to do all the correct studies in order to take it into humans.

Why did the foundation decide to fund this gene therapy work?

The foundation was established with the goal of eradicating these rare retinal blinding diseases. Leber's congenital amaurosis is one where after foundation-funded researchers understood the mechanism of the disease, it was determined that this was a good low-hanging fruit to go after. Now that we understand the mechanism and the way this disease progresses, we understand that if we put this one molecule back we can jump start those cells into working. Not all forms of LCA, not all forms of retinal degeneration are the same as this. We chose this along with others. These have been determined to be potentially gene therapy-able. This was the first one that actually made it forward into the clinic and showed very promising results.

Image: Dr. Stephen Rose

This post was originally published on Smartplanet.com

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