Scientists have shown for the first time that transplanting light-sensitive photoreceptors into the eyes of visually impaired mice can restore their vision.
The research suggests that transplanting photoreceptors - light-sensitive nerve cells that line the back of the eye - could form the basis of a new treatment to restore sight in people with degenerative eye diseases.
Scientists from UCL Institute of Ophthalmology injected cells from young healthy mice directly into the retinas of adult mice that lacked functional rod-photoreceptors. Loss of photoreceptors is the cause of blindness in many human eye diseases including age-related macular degeneration, retinitis pigmentosa and diabetes-related blindness.
There are two types of photoreceptor in the eye - rods and cones. The cells transplanted were immature (or progenitor) rod-photoreceptor cells. Rod cells are especially important for seeing in the dark as they are extremely sensitive to even low levels of light.
After four to six weeks, the transplanted cells appeared to be functioning almost as well as normal rod-photoreceptor cells and had formed the connections needed to transmit visual information to the brain.
The researchers also tested the vision of the treated mice in a dimly lit maze. Those mice with newly transplanted rod cells were able to use a visual cue to quickly find a hidden platform in the maze whereas untreated mice were able to find the hidden platform only by chance after extensive exploration of the maze.
Prof. Robin Ali at UCL Institute of Ophthalmology, who led the research, said: "We've shown for the first time that transplanted photoreceptor cells can integrate successfully with the existing retinal circuitry and truly improve vision. We're hopeful that we will soon be able to replicate this success with photoreceptors derived from embryonic stem cells and eventually to develop human trials.