In what could potentially prove to be a landmark in the field of optogenetics, a team of doctors from the Retina Foundation of the Southwest in Texas aims to restore vision in the blind patients suffering from Retinitis Pigmentosa.
Sponsored by RetroSense Therapeutics, a Michigan-based startup venture, it is going to be the first of its kind gene therapy treatment to permanently reverse the effects of acquired blindness.
Retinitis Pigmentosa is a form of acquired blindness where the light-sensitive photoreceptor cells in the retina no longer function properly due to damages suffered over a period of time. This degenerative disease initially affects the loss of peripheral and night vision, before eventually causing complete blindness.
What our brain cells interpret as vision is actually the ability of these specialized light-sensitive cells to distinguish between specific wavelengths of light and respond to them accordingly. The doctors are planning to use a groundbreaking neuroscience technique, known as optogenetics, in an attempt to precisely trigger the other retinal cells, known as the ganglion cells, to act in a similar way to the dead photoreceptor cells.
The procedure would involve injecting brain cells with a light-sensitive protein found in algae. Medically termed as channelrhodopsin, this protein helps algae to sense sunlight and move towards it. Doctors have engineered this light-sensitive protein to carry specific DNA instructions. By injecting this specifically coded protein into the surviving retinal cells, the doctors are hoping to turn them into replacement light sensors.
By principle, the procedure is similar to cardiac bypass surgery to a certain extent. Since the patients’ light-sensitive cells are damaged, the doctors plan to ‘bypass’ these cells and make the ganglion cells directly responsive to light.
However, since the channelrhodopsin protein has the ability to respond to light of a specific wavelength only, scientists believe that the successful implementation would result in restoring only monochromatic vision in the patients. In other words, they will only be able to see the world in black-&-white – without the ability to distinguish between different colors.
Nevertheless, the prospect of restoring vision in the blind, albeit partially, is a huge step forward. And the results so far appear to be promising. The technique has successfully been implemented to restore vision in blind mice and the doctors are now hoping to reproduce similar results in human beings as well.
It remains to be seen whether the trial will eventually taste success or not, but it’s undoubtedly an exciting prospect for the neuroscientists from all over the world. It can go a long way to reveal useful information about doing optogenetic studies in humans – something that can eventually lead to the successful treatment of Parkinson’s disease or severe mental illness using optogenetic therapy.