28.11.2013
Pressemitteilung: Eine neue Computersimulation für die Behandlung von Augenkrankheiten
Seit einigen Jahren gilt die Optogenetik als vielversprechende Therapie bei fortschreitender Erblindung, z.B. als Folge einer Netzhautdegeneration. Um diesen Therapieansatz weiterzuentwickeln, haben Marion Mutter und Dr. Thomas Münch vom Werner Reichardt Centrum für Integrative Neurowissenschaften (CIN) und dem Bernstein Center for Computational Neuroscience (BCCN) der Universität Tübingen ein Computermodell entwickelt, das das "optogenetische Sehen" simuliert. Die Forschungsergebnisse wurden in der Ausgabe vom 27. November in der Zeitschrift PLOS ONE veröffentlicht (Press release in English only).
Retinitis Pigmentosa is a form of retinal degeneration in which the photoreceptors in the eye die off. In order to counteract the accompanying loss of light perception, light-sensitive proteins known as channelrhodopsins are introduced into the retina using an optogenetic procedure. Every cell that contains channelrhodopsins can be activated by exposure to light. After optogenetic treatment, neighbouring cells can take over the lost functions of the photoreceptors. In fact, vision has already been successfully restored in mice in this way. Thus, in the last few years, the foundation has been laid for using optogenetics to treat blindness.
However, one also comes up against limits with this method. Human vision normally deals well with extreme contrasts of light levels in the environment: we are able to see in anything from weak starlight to glaring sunshine. In contrast, ‘optogenetic vision’ with channelrhodopsins would only work in the very brightest sunlight – at least with the variants of channelrhodopsin that have been developed so far.
Improving the characteristics of channelrhodopsins is something to be hoped for, above all from the point of view of developing potential future applications in humans. The researchers used a computer model they themselves developed to investigate how to achieve these improvements. This model makes it possible to assess how well different variants of channelrhodopsin would support restoring a sense of vision. “When one of these molecules is activated by light, it cycles through a defined set of states which ultimately determine the light response of the treated eye”, explains Marion Mutter. Previously, improvements to channelrhodopsin were mainly pursued to carry out research into basic neurobiological questions. “Our results show that optogenetic vision would benefit from completely different improvements which have so far been overlooked,” according to Marion Mutter and Thomas Münch.
What effects would these improvements have on the sense of vision? “According to our calculations, it should be possible to see in brightness conditions that are hundred-fold dimmer than what would currently be possible”, explains Thomas Münch, leader of the project. According to his estimates, this would allow patients treated with optogenetic techniques to be able to see not only in sunlight, but also in a well lit room. “At these brightness levels we reach the biophysical limits of what is possible with classical channelrhodopsin molecules”, says Münch. “However, in our study we could also show why there are these limits, and so we provide a direction for novel types of improvements in the future.”
Press release for download only in German. Pressemitteilung zum Download nur in Deutsch.
Organization:
- Werner Reichardt Centre for Integrative Neuroscience
- Bernstein Center for Computational Neuroscience
Reseach Group: Retinal Circuits and Optogenetics