Scientists near cure for blindness

• Revolutionary stem cell transplant restores vision in mice

Scientists plan to carry out clinical trials in humans with worsening vision, following ‘exciting’ research on mice to treat blindness.

Mice, which had lost sight after suffering retinal degeneration, were able to detect light after having stem cell transplants.

While researchers cautioned that restoring sight in people was some way off, they have proposed to move on to human trials after further animal testing.

The mice in the study were transplanted with stem cells which had been grown into small patches of light-sensitive retina – the thin layer of tissue lining the back of the eye.

The research, from the RIKEN institute in Japan, is said to be the first time photoreceptors – the light-sensitive neurons in the eye – have been successfully transplanted to host cells and sent visual signals to the host retina and brain.

Dr. Michiko Mandai, who led the study, said: “Transplanting retinal tissue instead of simply using photoreceptor cells allowed the development of more mature, organised morphology, which likely led to better responses to light.”

The study, published in Stem Cell Reports, showed mice who had implants were able to make associations with light, provided that a substantial amount of the transplant was located in the correct place.

The authors said this showed the new cells in the retina not only responded to light but also that the information travelled to the brain and could be used to learn. Professor of Ophthalmology at the University of Oxford, Robert MacLaren, said the research gave hope for people with poor sight.

He said: “This study is exciting because it shows that a complicated part of the central nervous system, such as the retina, could potentially be regenerated from something as simple as a skin cell. Furthermore, the engineered retinal tissue appears to be able to make connections to the brain after transplantation. Clinical treatments are still a long way off but, for patients with retinal degeneration, this provides some hope for the future.”

How does it work? The mice in the study were transplanted with stem cells which had been grown into small patches of light-sensitive retina – the thin layer of tissue lining the back of the eye.

Dr. Michiko Mandai said: “Transplanting retinal tissue instead of simply using photoreceptor cells allowed the development of more mature, organiaed morphology, which likely led to better responses to light.”

Mice who had implants were able to make associations with light, provided that a substantial amount of the transplant was located in the correct place.

What is retinal degeneration? Retinal degenerative diseases all involve damage to photoreceptor cells of the retina, which malfunction and disappear.

Photoreceptor cells are the light sensing cells of the retina, that lines the back of the eye. Normally, the retina’s photoreceptor cells sense light, initiating a cascade of electrical impulses that are sent through the retina and the optic nerve to the brain to create an image.

When the photoreceptor cells malfunction due to the degenerative disease, the image that is received is blurred, distorted or completely unseen.

This is often a progressive disease in which the person will suffer a continuous decline in vision.

*Adapted from DailyMailUK Online