London, April 28 : Swiss researchers have successfully treated blind mice to sense light by inserting a protein derived from algae into their eyes.
Botond Roska of the Friedrich Miescher Institute for Biomedical Research in Basel hopes that a similar therapy may one day be available for treating certain forms of blindness in humans.
He and his team used for the treatment the channelrhodopsin-2 (ChR2) protein, which is known to enable algae to sense light for photosynthesis.
The researchers experimented on mice whose eyes were entirely missing photoreceptors, a hallmark of several human conditions like age-related macular degeneration.
Photoreceptors are known to feed signals about light to the next layer of cells, called bipolar cells, before a signal is relayed on to the brain, providing a visual image.
The research team used a harmless virus to carry the protein into the mice's bipolar cells.
Although the protein ended up in only about seven per cent of the cells through that procedure, it was enough light signals to be transmitted to the next layer of the retina and eventually the brain.
The researchers then placed the treated as well as untreated mice in the dark, and suddenly turned on a bright light.
While the treated mice jumped into action when a bright light was turned on, those untreated did not respond to light at all.
Thereafter, the mice were shown a series of moving stripes, and it was observed that the treated mice were better than their untreated counterparts in following the stripes.
Roska, however, admits that it is difficult to gauge exactly how well the mice could see after the treatment.
"You can't ask the mouse," Nature magazine quoted him as saying.
He and his colleagues are now joining hands with other clinical groups to develop the technique for people.
Even if they succeed in their efforts, the therapy is likely to be a last-chance treatment.
Roska says: "The method should only be used if there's absolutely no vision left."