Scientists have successfully given blind mice the ability to perceive light. The development raises hope that it may some day be possible to restore sight to people with diseases that lead to blindness.
The loss of light-sensing, photoreceptor cells is responsible for blinding diseases such as macular degeneration, diabetes and retinitis pigmentosa.
It's always been thought that stem cell transplants could cure retinal eye diseases since no other part of the eye is damaged. Stem cells are master cells in the body that can be harvested and coaxed to grow into any tissue in the body.
But attempts at such therapies to manufacture new photoreceptors have failed. That is, until now, according to Jane Sowden of University College London Institute of Ophthalmology.
"The work is very significant for the development for stem cell therapies, particularly for patients with untreatable eye diseases," said Jane Sowden.
Sowden is part of a team of British and US researchers that has successfully transplanted stem cells into mice with damaged photoreceptors, giving the blind rodents some vision.
Sowden say the key to scientists' success was introducing the immature stem cells at the moment they were transforming into retina cells.
"Our work has shown remarkably that the mature retina is able to support the development of the new photoreceptors," she said. "And it was very exciting when we saw the first views of the beautifully integrated, new photoreceptors within the adult retina."
Sowden made her comments in an interview with the editors of the journal Nature, which also published the research.
So how did scientists know the mice could see? Co-author Rachael Pearson, of the Institute of Child Health at University College in London, says researchers looked at the rodents' pupils.
"Pupil constriction requires the detection of light by photoreceptors," said Rachael Pearson. "And we found that the transplanted cells could restore this reflex in mice that normally lacked it."
Scientists say the challenge now is to figure out a way to grow large numbers of photoreceptor cells in the laboratory from individual patients with degenerative eye diseases and extract stem cells that can be given back to them.
Experts say the development could have implications for the treatment of other neurological diseases.