The Friedrich Miescher Institute of the Novartis Research Foundation (FMI) announced a novel technique that restores light sensitivity to previously unresponsive retinas in blind mice and, remarkably, produces light-induced behavioral change in mice with retinal damage. A study on the technique indicates that the approach could be an alternative to surgical transplantation of electrode arrays.
“We are excited and encouraged by the results of the study, which open the way for clinical trials in humans,” said Susan M. Gasser, Director of FMI. “The new technique developed at the FMI could revolutionize the way that retinitis pigmentosa and late-stage macular degeneration are treated, potentially eliminating the need for surgery.”
The research team headed by Botond Roska of FMI, in collaboration with Connie Cepko of Harvard Medical School, adopted a novel approach by administering a gene of a light-activated protein from green algae to selected retinal cells (ON Bipolar cells). Their innovation involves the selective restoration of light sensitivity to circuits that respond to increases in light level (ON circuits) and not those that respond to decreasing light levels (OFF circuits). Treatment of blind mice with this technique enabled them to successfully perform visually guided behavioral tasks, an unprecedented result.
Retinitis pigmentosa is a group of inherited retinal diseases that affects about 100,000 Americans and 1.5 million people worldwide. It causes the progressive deterioration of specialized, light-absorbing cells in the retina, the paper-thin tissue that lines the back of the eye like film in a camera.
“Contrary to common belief, the retina is a complicated organ, with more than 50 types of neurons, performing sophisticated image processing tasks,” says Botond Roska, lead investigator of the study at FMI. “By targeting a select population of these retinal neurons, we have been able to restore a meaningful response to light.”
Today’s research announcement is a major breakthrough in the possible treatment of one of the most devastating losses of human sensory conditions, and offers hope for treatment of a disease that frequently goes unnoticed until it has progressed past the point of treatability. Unlike other forms of retinal degeneration, retinitis pigmentosa initially inhibits night and peripheral vision, and therefore goes undetected by most afflicted with it until it has reached later stages, when it significantly limits all types of vision. The technique pioneered at FMI can also be used to treat late-stages of macular degeneration, in which photoreceptor function has been lost.
“This research opens a new plane of investigation, and offers hope for the millions affected by blindness due to retinitis pigmentosa and late-stage macular degeneration,” said Jose Sahel, a leading ophthalmologist in the field of retinal degeneration. “We expect these findings will become increasingly valuable as the global population ages, given that these conditions are particularly acute among the elderly. Photoreceptor restoration would be a highly desirable alternative to surgical implantation of light sensing arrays, which is the only current option for retinitis pigmentosa patients.”
Illustration: Microsoft clipart.
Friedrich Miescher Institute for Biomedical Research Media Release (04/28/08)
Edu Bourse (04/28/08)
Medical News Today (04/28/08)
Technology Review (05/01/08)
Abstract (Nature Neuroscience, published online: 27 April 2008)