Mice suffering from night blindness had their vision restored after scientists from University College London injected light-sensitive photoreceptors directly into their retinas.
The mice – models for diseases like retinitis pigmentosa and diabetes-related blindness – lacked functional rod-photoreceptors. They are able to see in normal light but are blind in dim light. Adult mice had immature or progenitor rod-receptor cells – which are important for seeing in low levels of lights – transplanted directly into their retinas.
After four to six weeks, the transplanted cells were functioning almost as well as normal rod-photoreceptor cells and had formed connections needed to transmit visual information to the brain.
“We’ve shown for the first time that transplanted photoreceptor cells can integrate successfully with the existing circuitry and truly improve vision,” said Professor Robin Ali from the Institute of Ophthalmology, who led the research. “We’re hopeful that we will soon be able to replicate this success with photoreceptors derived from embryonic stem cells and eventually develop human trials.”
The researchers – who published their results in Nature – tested the vision of the treated mice in a dimly lit maze. Those with newly transplanted rod cells used a visual cue to quickly find a hidden platform – untreated mice only found the platform after extensive exploration of the maze.
“This is a landmark study that will inform future research across a wide range of fields including vision research, neuroscience and regenerative medicine,” said Dr Rob Buckle, head of regenerative medicine at the Medical Research Council, who partly funded the research.
“It provides clear evidence of functional recovery in the damaged eye through cell transplantation, providing great encouragement for the development of stem cell therapies to address the many debilitating eye conditions that affect millions worldwide.”
The team are now looking for ways to improve the efficiency of cone photoreceptor transplantation and to increase the effectiveness of transplantation in very degenerate retina.