Gene Therapy Revives Cones Long After They Stop Working

If you could do one thing for a person losing their vision to a retinal disease, saving their cones would be near the top of the list. That’s because cones are the retinal cells that allow people to see color and fine detail, enabling them to drive, read and see the faces of loved ones.

A Foundation-funded research collaboration from the Institut de la Vision in Paris and the Friedrich Miescher Institute in Basel, Switzerland, is developing a gene therapy that revives degenerating cones, enabling them to regain their ability to respond to light and provide vision. The treatment also improves the health of cones and extends their lifespan significantly. A key benefit of the approach is that it may help people affected by a range of conditions, because it works independently of the underlying disease-causing genetic defect. The collaboration’s goal is to move the gene therapy into a clinical trial within three years.

In 2010, the investigative team showed that their treatment was effective and well sustained in both slow and fast models of retinal degeneration in mice. The scientists performed visual behavior and retinal sensitivity tests to demonstrate that the mice regained functional vision after treatment.

The therapy involves delivery of a gene to cones that leads to the production of a microbial protein called halorhodopsin, which restores light sensitivity. In retinal degenerative conditions, such as retinitis pigmentosa, cones remain present for a long time after they stop working.

To move the treatment into the clinic, the researchers will test the treatment in large animal models and adapt it for use in humans. The team is already putting together a patient screening protocol — which includes imaging, visual field testing and evaluation of retinal sensitivity — to identify people who may be eligible for the forthcoming clinical trial.

The Foundation is providing nearly $1.5 million in funding over three years for the project.