New photoswitch therapy restores useful vision in blind animals

Retinitis pigmentosa is a particularly terrifying form of late onset blindness, in which the sufferers vision slowly degrades from the periphery, in. Your view of theworld slowly narrows to a point, and one can only imagine the frustration such a slow, torturous process would create.

These sorts of degenerative diseases are often attacked from the preventative side, which gives thema spectrum of possible successes, from total prevention to simple prolonging of the process tobuy more time with sight. Usually, trying to cure something is much more binary, with a cured-or-not logic that doesnt tend to reward partial successes. Anew study looking at certain types of blindness in lab animals may have made just such an interactive step forward, however, restoring light sensitivity in eyes that havent seen for some time.

The crux of the insight is a type of molecule called a photoswitch. As the name implies, a photoswitch is a molecule that responds in a back-and-forth manner to the presence or absence of light. In this case, the molecules switch in terms of their physical shape, flipping back and forth between a larger and a more compact state put them in the right place, and these shape changes can even control a nerve cellsability to fire. More to the point, it allows otherwise light-insensitive cells to havea blunt response to light use these photoswitches to control firing in retinalcells that arealready hooked up to the optic nerve? This study suggests thatthe brain can make some use of thisnew information.

The therapy works by using a modified virus viruses being natures specifically tailored genetic injection tools to insert a modified surface receptor gene into diseased retinal cells. This receptor, whenactivated, induces the neurons to fire, and has been modified to bind tothe studys photoswitch molecules, rather than its natural ligand. This means that when light hits the eye, the photoswitches change shape, opening the channels, allowing ions to flow, and inducing the cell to fire. As you can imagine, this is a blunt sort of response all the cells fire in response toany incoming light past a certain threshold. Animals that underwent the procedure could reliably distinguish light from darkness, and flashing from solid light.

The treatment was used on both mice and dogs, and seemed to work equally well in both, which of course raises hopes for easy generalization to humans. It would make sense, since the eye and the most associated genes in this case are highly conserved throughout mammals, with mostlylarge-scale structural changes rather than radically different use of proteins. Light sensitivity might not seem like the biggest deal in the world, but simply being able to orient yourself relative to a window or other light source, or notice that something has moved between you and a light, can have a huge impact on the ability to get around. In the land of the blind, the light-sensitive man is at a slight advantage.

Whats nice about this therapy is that it sort of forces in a whole new form of sight, almost creates a fundamentally new type of eye out of the remnants of anold one. Thismeans that, as long as there are some living retinal cells left, they could be restored to light sensitivity; by not trying to undo the specific damages of a particular disease, theyve created a therapy that could be of use to people suffering all sortsof damage. It shows the power of modern genetic engineering, as the researchers were able to force cells to express the proteins their approach required. And it shows why nobody, in this age of wonders, should assume theyre beyond the help of medical science.

Now read: Scientists discover new layer in human eye we never knew existed

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New photoswitch therapy restores useful vision in blind animals