Photoreceptor transplant restores vision in mice
Author:Science and Technology Division, UK
Article Source:Adapted from: The Medical Research Council 18th April 2012
Scientists funded by the Medical Research Council (MRC) have shown for the first time that transplanting light-sensitive photoreceptors into the eyes of visually impaired mice can restore their vision. It is predicted that this finding could form the basis of a new treatment to restore sight in people with degenerative eye diseases.
There are two types of photoreceptor in the eye – rods and cones, which line the back of the eye. Rod cells are especially important for seeing in the dark as they are extremely sensitive to even low levels of light. Loss of photoreceptors is the cause of blindness in many human eye diseases including age-related macular degeneration, retinitis pigmentosa and diabetes-related blindness. Scientists from UCL injected cells from young healthy mice directly into the retinas of adult mice that lacks functional rod-photoreceptors. 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.
In order to test whether the vision of the mice has improved, the researchers tested the vision of the 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.
The researchers explained that this research has shown for the first time that transplanted photoreceptor cells can integrate successfully with the existing retinal circuitry and truly improve vision. It is hoped that this success can be replicated with photoreceptors derived from embryonic stem cells and eventually developed into human trials. In addition, these 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.