Stem cell treatment restores light sensitivity in blind mice

Scientists have partially reversed blindness in mice using lab-grown retinas made from skin cells.

By transplanting this retinal tissue they were able to achieve much better results than have so far been achieved with simply injecting retinal cells – half the mice in the study had their sensitivity to light restored.

The scientists at Japan's RIKEN Centre for Developmental Biology first turned skin cells into induced pluripotent stem cells (iPSCs), which were turned into retinal cells, which were in turn grown into a thin layer of retina.

These light-sensitive layers were transplanted into 21 mice with damaged retinas, similar to what is seen in the age-related macular degeneration in humans – the principle cause of blindness in people over 50.

'At first glance, I almost thought I was looking at a [healthy] retina, not the degenerated retina with transplants,' Dr Michiko Mandai said of her reaction to seeing the retinas for the first time. 'I was so surprised and excited to see these tissue could develop into a beautifully structured photoreceptor layer, with the most perfect morphology,' she told Smithsonian.com.

They then demonstrated that these retinal layers actually joined up with the mice's own retinas and restored some sensitivity to light. The mice with restored retinas were able to respond to light signals that warned them to move away to avoid an electric shock.

'No one has really shown transplanted stem cell-derived retinal cells responding to light in a straightforward approach as presented in this study. We collected data to support that the signal is transmitted to host cells that send signals to the brain,' said Dr Mandai.

The scientists said that it took around a month after transplantation for the retina to begin to respond, and they think that this would translate to five or six months if it were used in humans. They hope to begin clinical trials of this approach in the next two years.

'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,' Professor Robert MacLaren, a consultant ophthalmologist at the University of Oxford who was not involved in the study, told the Mail Online.

'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,' he added.