‘Blind’ Mice Eyesight Treated With Transplanted Cells
British scientists have restored the sight of blind mice by transplanting light-sensitive photoreceptor cells into their eyes.
The work is a step towards a new treatment for patients with degenerative eye diseases.
Scientists at University College London Institute of Ophthalmology injected cells from young healthy mice directly into the retinas of adult mice that had night-blindness.
The findings are published in Nature.
The cells transplanted were immature rod-photoreceptor cells, which are especially important for seeing in the dark.
After four to six weeks up to one in six of the transplanted cells had formed the connections needed to transmit visual information to the brain.
Hidden platform
The researchers tested the vision of the treated mice in a dimly-lit water maze.
Those mice with transplanted rod cells were able to see a visual cue to find a hidden platform to enable them to get out of the water. This was in contrast to untreated mice who found the platform only by chance after lengthy exploration of the maze.
Prof Robin Ali, at UCL Institute of Ophthalmology and Moorfields Eye Hospital, 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.”
Prof Ali said the behavioural maze test was “ultimate proof” that a significant amount of vision had been restored in the treated mice.
But although the results appear promising, there are still many steps to go before such a treatment might be suitable for patients.
There are two types of photoreceptor in the eye - rods and cones. It has so far proved harder to transplant cone photoreceptors - which are crucial for human sight and tasks like reading.
The scientists also plan to experiment with photoreceptors derived from embryonic stem cells. Prof Ali said such cell lines already exist but the question is how efficiently they can transplant them.
The findings could have implications for treating humans
Loss of photoreceptors is the cause of blindness in many human eye diseases including age-related macular degeneration (AMD), retinitis pigmentosa and diabetes-related blindness.
But many more animal studies will be needed before such a technique would be tried with humans.