Gene therapy shows promise for reversing blindness

The breakthrough research involved scientists reprogramming cells in the back of the eyes of blind mice. They achieved this by using a viral vector to express a light-sensitive protein called melanopsin (OPN4), found in the damaged residual retinal cells of mice with retinitis pigmentosa (RP).While the mice had previously lost millions of light sensitive photoreceptors due to RP, the cells expressing melanopsin were able to respond to light and send visual signals to the brain.{{quote-a:r-w:400-I:2-Q:“There are many blind patients in our clinics and the ability to give th some sight back with a relatively simple genetic procedure is very exciting.”-WHO:Dr Samantha de Silva}}After 13 months, the mice had restored varying levels of pupil light reflex and behavioural light avoidance, allowing th to perform tasks that required basic image recognition. Additionally, as melanopsin is already present in the eye, the team believes it is unlikely to generate an immune response when introduced via gene therapy.“There are many blind patients in our clinics and the ability to give th some sight back with a relatively simple genetic procedure is very exciting. Our next step will be to start a clinical trial to assess this in patients,” study lead author Dr Samantha de Silva said.The Oxford team has also been trialling an electronic retina successfully in blind patients, but the genetic approach may have advantages in being simpler to administer.The research team was headed by professors Robert MacLaren and Mark Hankins from the Nuffield Laboratory of Ophthalmology in Oxford, together with de Silva, and the scientists hope to commence human trials within five years.More reading: The full report.