To this end the researchers injected healthy and young mice cells directly in the retinas of adult mice lacking of functional rod photoreceptors. The reason is that the loss of photoreceptors is the cause of blindness in many human eye diseases such as age-related degeneration, retinitis pigmentosa or diabetes-related blindness.
After a period of 4 to 6 weeks, the researchers found that the transplanted cells functioned in the same way as normal rod photoreceptors and had made the necessary connections to transmit visual information to the brain.
Not only that, the scientists also tested the vision of the treated mice in a maze in low light. Mice with newly transplanted cells were able to use a visual cue to quickly find a hidden platform in the maze. In contrast, untreated mice were also able to find the hidden platform but in this case by chance after extensive exploration of the maze.
Professor Robin Ali, director of research:
"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.
"Although there are many more steps before this approach will be available to patients, it could lead to treatments for thousands of people who have lost their sight through degenerative eye disorders. The findings also pave the way for techniques to repair the central nervous system as they demonstrate the brain's amazing ability to connect with newly transplanted neurons."
An amazing result which indicates that transplanted photoreceptor cells can be successfully integrated into the circuitry of the retina and improve vision. The dream of regaining sight in humans may have found a possible solution.