In publica commoda

Press release: Light in sight

Nr. 105/2015 - 07.05.2015

Scientists develop molecular light switch as a potential therapy for acquired blindness

(pug) Scientists from the Universities of Bern in Switzerland and Göttingen in Germany have succeeded in restoring vision to blind mice. Hereditary blindness caused by a progressive degeneration of the light-sensing cells in the eye, the photoreceptors, affects millions of people worldwide. Although the light-sensing cells are lost, cells in deeper layers of the retina, which normally cannot sense light, remain intact. The scientists now introduced a new light-sensing protein into the surviving retina cells, thus turning them into “replacement photoreceptors”. The results were published in PLoS Biology.

“We were asking the question, ‘Can we design light-activatable proteins that gate specific signaling pathways in specific cells?’, in other words, can the natural signaling pathways of the target cells be retained and just modified in a way to be turned on by light instead of a neurotransmitter released from a preceding neuron?”, says Dr. Sonja Kleinlogel, corresponding author of the paper whose research group is based at the University of Bern.

The scientists molecularly modified the cells that normally would have received direct information from the photoreceptors in a way that they reacted to light stimuli instead of chemical signals, thus turning them into “replacement photoreceptors”. Integrating a new “light antenna” into the surviving cells has the advantage that signal computation of the retina is maximally utilized. “Using optical imaging of neuronal activity in the treated mice, we showed that these replacement photoreceptors were able to activate the visual cortex – the part of the cortex that analyzes visual signals – more strongly again,” say Prof. Dr. Siegrid Löwel and Dr. Justyna Pielecka-Fortuna, neuroscientists at the University of Göttingen.

The result: The mice were able to see under daylight conditions, react to visual stimuli and learn visually triggered behaviors. “The new therapy can potentially restore sight in patients suffering from any kind of photoreceptor degeneration,” says Dr. Kleinlogel. “The major improvement of the new approach is that patients will be able to see under normal daylight conditions without the need for light intensifiers or image converter goggles. However, it will take at least another two or three years before the new ‘light antenna’ can be tested in the clinical setting.” Furthermore, the novel principle opens a whole palette of new possibilities to potentially treat conditions such as pain, depression and epilepsy.

Original publication: Van Wyk et al. Restoring the ON-switch in blind retinas: Opto-mGluR6, a next-generation, cell-tailored optogenetic tool. PLoS Biology 2015. Doi: 10.1371/journal.pbio.pbio.1002143.

Prof. Dr. Siegrid Löwel
University of Goettingen
Department of Systems Neuroscience
Von-Siebold-Straße 6, 37075 Göttingen, Germany
Phone +49 551 39-20161/-20160

Dr. Sonja Kleinlogel
University of Bern
Department of Physiology
Optogenetics Group
Bühlplatz 5, 3012 Bern, Switzerland
Phone +41 31 631 8705