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Case study: Gene therapy for blindness

Eye

The use of genetic therapy to treat advanced retinal degeneration and blindness is a fast developing area of medical science, in response to the needs of an increasingly elderly population across the world. Our contribution to this research drive involves developing a new type of gene therapy to reprogramme cells deep in the eye to sense light. The ultimate aim is to treat all types of blindness caused by damaged or missing rods and cones, the eye’s light receptor cells.

retina
Degeneration of the retina is a common cause of blindness

Research by Professor Rob Lucas from our Faculty of Life Sciences focuses on how mammals detect and measure light, and how humans detect differences in the amount of light we are exposed to between day and night.

He explains: "This is all about understanding vision in its most basic sense, and we are finding out new things all the time. For instance, people once thought you could explain everything through particular cells, but our work has discovered that there are different cells in the retina which respond to light in different ways.

"In collaboration with Professor Paul Bishop, we have applied this knowledge to developing ways of treating people with retinal degeneration. Degeneration of the retina is a common cause of blindness and, because the retina is part of the central nervous system, when its cells die they don’t grow back."

Gene transfer

Professor Lucas says it would be impossible to recreate in a dish or model on a computer what his research is seeking to achieve.

"Essentially, there are mice that have the same conditions that people go blind with. Although it has long been known that mice can go blind, it is only relatively recently that there have been viable approaches to restoring vision in mice. There are numerous ways in which we now think this might be possible. We have moved from understanding why mice become blind to trying to treat them."

If we can get something in that retina responding to light, then the retina can start giving information to the brain again. In treating mice we are using methods that could be applied to humans, and developing therapies and seeing if they work is the critical first step.

Professor Rob Lucas / Professor of Neurobiology

These developments have been made possible by advances in gene transfer technology.

For instance, the team injects into blind mice the human gene for rhodopsin, a pigment that detects light. This enables other cells that lie deeper within the retina to capture light. By giving these cells the ability to produce their own light-detecting pigment, they can to some extent compensate for the loss of rods and cones.

After treatment, Professor Lucas says, it was found that mice could detect patterns presented on computer monitors, although not as well as sighted mice. "In earlier attempts, mice could only respond to extremely bright light, so this new finding is significant. This is also the first time a human gene has been tested this way."

Moving towards human treatment

The virus used to deliver the gene therapy is already approved for use in humans. Professor Lucas says that plans are in place to move this therapy forward to an approach that may lead to a human trial of this treatment within the next five years.

As he adds: "If we can get something in that retina responding to light, then the retina can start giving information to the brain again. In treating mice we are using methods that could be applied to humans, and developing therapies and seeing if they work is the critical first step."