Three Blind Mice No Longer, Adult Stem Cells Restore Sight
By Christian Nordqvist, Medical News Today, November 8, 2006
Scientists from the Institutes of Ophthalmology and Child Health (University College London) and Moorfield's Eye Hospital in London performed retinal stem cell transplants on blind mice in an attempt to restore their vision. The procedure was successful and reversed their condition. Humans blinded by diabetes or age-related macular degeneration have renewed hope as the results of this study could ultimately lead to sight restoration for those individuals.
The journal Nature has published the complete study.
The mice suffered from a type of eye damage which is a common cause of human blindness – photoreceptor loss.
Preventing or delaying the loss of the cone and rod photoreceptors is the existing focus of treatment for individuals who are losing their eyesight. But for people who have already lost their vision, there is no present medical procedure to restore their sight. The study may help blind individuals regain the cone and rod photoreceptors in the retina – and see again.
Connections to the brain are there even when the photoreceptors are gone, so in the world of cell transplant, the retina is considered to be a good candidate. Some of the parts may be missing, but he wiring is still there. Previous trials were unable to develop photoreceptor cells because the cells were too immature.
This time, the cells were set up so that they would develop into photoreceptors. The transplant cells were still immature, but less so than before in the new study. 3-day-old mice provided the cell samples from the retina. The blind mice were then given the cells via transplant directly into the eyes.
Gradually, the mice began to recover their eyesight. Scientists were able to conclude this because when the mice were exposed to light, their pupils contracted.
The scientists aim to find a way of using adult stem cells in order to see whether this can be done with humans. Another method would be to use cells from a fetus that is 3-6 months old; however, the scientists will not pursue this avenue for ethical reasons.
The scientists say that adult retinas have areas with cells that might be usable. They also added that there will be extensive research before and reliable medical procedure is offered to patients.