Scientists at University College London (UCL) have been undergoing a huge project, led by Professor Robin Ali. They are conducting research into how sight can be restored to the blind through the transplant of light detecting cells into the eye.
Research has been confined to mice studies so far, but hopes are that their conclusions will bring about gradual, controlled human testing.
What Was Done?
The experiment involved a group of 27 adult mice that were bred with a genetic mutation that led to blindness in dim lights (also called ‘night blindness’) and a control group of young, healthy mice.
Scientists conducted a transplant of cells from the young mice to the adult mice, giving them ‘light sensitive rod-photoreceptor cells’. These are the cells in the eye that detect and respond to light and enable sight.
The transplanted cells were ‘immature’. This means that they weren’t fully developed, and so would be able to form vital connections to the adult mouse’s brain as they matured.
It was found that within 4-6 weeks, in 1 in 6 of the treated mice, the transplanted cells had formed the connections needed to transmit vital information to the brain for sight to be possible.
How Did They Test This?
The impact that this surgery had on the mice’s vision was tested using a dim-lit water maze.
They were placed in the water, and had to swim around until they found a ‘hidden platform’. In all of the experiments a visual cue (a light) was situated just above the platform to attract the mice in that direction.
The mice were all tested individually, and the results were compared between the adults with restored vision through transplant and the adults who still had night blindness.
It was found that 70% of the treated mice identified the platform almost immediately. Those who still had impaired vision struggled to find it at all and often swam aimlessly through the water (see video).
This shows that the treated mice, who had once suffered from night blindness, were now responsive to light.
Can This Be Used To Help Humans?
There is still a long way to go before this can become an option for helping restore sight to humans. This is because while mice have only 1 type of light detecting cell in their eye, humans have 2. These are:
Rod cells: These allow sight in low light or night time conditions (this is the type of cell that the mice had transplanted).
Cone cells: These help define colour detail, and enable sight in brighter conditions.
Even once this procedure is ready for human testing, further complications arise. For example, there are no indications that this type of transplant would help somebody that had vision issues that were non-related to the rod-photoreceptor cells.
This surgery wouldn’t restore full vision to a human, only the ability to see in low light conditions. They would still struggle to see clearly or in detail (and engage in activities such as reading) or see in bright conditions.
However, this is a major scientific milestone as it shows that sight can be restored by transplant of cells. This is only the first phase of a major effort to apply this research to help restore vision in humans, and looks to have a very promising future.
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Steph McLean is blogging to increase awareness of eye health issues and news, and works for Lenstore, an ecommerce retailer selling contact lenses online. Lenstore also has in-house Optical Advisors and Opticians to help support their customer’s needs.