Michigan-based startup Retrosense Therapeutics wants to restore vision in blind patients with a gene therapy that gives light sensitivity to neurons that don't normally possess it. Technology Review reports.
With the technique called optogenetics, specific neurons or proteins are targeted using light. Over the last few years, scientists have used the technique to study brain circuits and the neural control of behavior by directing neuron activity with flashes of light. Genetically engineered mice, for example, could have neurons that express light-activated proteins.
The idea behind Retrosense's experimental gene therapy is to use optogenetics to get other cells in the retina (cells that typically don’t respond to light) to take the place of the dying rods and cones (the cells which convert light into electrical signals).
They focused on ganglion cells, which don't normally respond to light. These act as a conduit for electrical information sent from the retina's rods and cones, transmitting visual information directly to the brain. They also survive long after rods and cones are lost.
- Doctors would inject a (non-disease causing) virus into a patient's eye.
- That virus would carry the genetic information needed to produce the light-sensitive channel proteins in the ganglion cells.
- Normally, rods, cones, and other cells translate light information into a code of neuron-firing patterns that is then transmitted via the ganglion cells into the brain. Since this therapy would bypass that information processing, it may require the brain to learn how to interpret the signals.
Currently, there are no approved therapies to treat patients who have lost their vision due to dry age-related macular degeneration and inherited retinal degenerative diseases such as retinitis pigmentosa.
So far, the treatment restored some vision-evoked behaviors in rodents and also seems safe in nonhuman primates (the optogenetically modified ganglion cells of these primates are light-responsive, but there are no nonhuman primate models of retinal degeneration).
Retrosense plans to begin its first clinical trial with 9 blind retinitis pigmentosa human patients in 2013.
[From Technology Review]
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