Imperial to lead German and Irish researchers in £2M optogenetics project

Scientists at Imperial College London are to take part in a £2 million project to develop a new genetic engineering technique called optogenetics that could lead to a new treatment for the hereditary eye condition, retinitis pigmentosa.

Retinitis pigmentosa (RP) is a group of hereditary eye disorders affecting approximately one person in every 3,500. In the early stages it causes poor night vision, leading on to tunnel vision, which gradually worsens until there is a total loss of sight. RP inactivates the rod cells in the eyes, which are important for night vision. As RP progresses the cells die and this eventually results in the loss of remaining light-sensitive cells.

The aim of optogenetics is re-engineer nerve cells in the eye so that they are activated by light, rather than by electrical impulses. It is hoped would make it possible to send visual information to the brain even when all the original light sensitive cells are no longer working.

This builds on research over the past twenty years that has investigated the use of implanted electronic chips to restore vision. The researchers behind the new project say their approach will enable more complex visual information to be sent to eye than is possible with these implants.

The new optogenetic technique will enable researchers to target individual cells, making different types of cells sensitive to different wavelengths of light. The technique involves genetically altering nerve cells to express a protein called channelrhodopsin. This is a light sensitive ion channel which allows the cell to be activated with short pulses of light, while a complementary protein called halorhodopsin can in turn be used to inactivate cells.

The researchers will use viral vectors to target channelrhodopsin into the eye. Subjects will wear spectacles that emit light to switch the nerve cells on and off. These glasses will incorporate a miniature video camera that records information about the wearer’s surroundings. This information will be sent to micro-sized light emitting diodes embedded in the glasses, sending pulses directly into the retina. The wearer’s re-engineered nerve cells will receive the encoded information, activating the cells to send the messages to the visual cortex in the brain for processing, restoring vision.

The researchers hope that success in this project will allow them to move towards clinical trials of the new technology within the next five to ten years. To date they have demonstrated the use of channelrhodopsin to make retinal cells and neurons in mouse models light-sensitive. Initial prototypes of a micro light emitting diode array have also been made and it has been shown the arrays can switch the cells ‘on’ and ‘off’ using tiny pin-pricks of light in the laboratory.

Research partners at the Max-Planck Institute for Biophysics and the Friederich Miescher Institute will develop now new types of enhanced channelrhodopsin and methods of delivering them into the eye.

At the same time, Imperial researchers and scientists from the Tyndall Institute in Ireland will develop the opto-electronic array.

The European Commission funded project is coordinated by Patrick Degenaar, from the Centre of Neuroscience and the Institute of Biomedical Engineering at Imperial College London. The team includes Ernst Bamberg from the Max Planck Institute of Biophysics, Botond Roska from the Friederich Miescher Institute for Biomedical Research, Mark Neil from the Physics Department, Imperial College London, Brian Corbett from the Tyndall National Institute at University College Cork in Ireland and Scientifica Limited.