Stem Cells May Cure Most Common Cause of Blindness

Age Related Macular Degeneration (ARMD) is the leading cause of sight loss in the UK, and over 600,000 Britons are currently affected by the condition (NHS, 2015). The macular is an area of the eye which provides sharp central vision. Although the cause for degeneration in this area isn’t known, it is suspected that free radicals play a role. Other than ensuring the diet contains a high level of antioxidants, there are not many options for preventing the condition and it does not have a cure.

ARMD under the microscope

That may change very soon with the announcement of a breakthrough using stem cells, which could give hope to those who suffer with the condition. Professor Gilbert Bernier and his team at the University of Montreal have managed to synthesise photoreceptors (vision cells) though the manipulation of embryonic stem cells.

Stem cells are a type of cell which can transform into anything, such as a nerve cell, a muscle cell, or a skin cell. Bernier’s team have harnessed this ability to create cones, a type of vision cell which is responsible for colour sensitivity and visual ‘acuity’ or sharpness. They make up a large number of the cells within the macular but if they become damaged they cannot be replaced. Creating these cells in the lab may provide a way for returning vision to those with ARMD because they could be transplanted into the eye to replace damaged or dead cells.

Rod (blue) and cone (purple) cells under an electron microscope. Credit: Steve Gschmeissner

The cones were synthesised following the application of a protein called COCO to the stem cells. COCO is a molecule which is normally expressed in photoreceptors during their development. By applying COCO to stem cells, the signals which cause retinal cells to differentiate between multiple cell types is blocked, leading to the creation of a specific type of cell; in this case, cones. COCO can systematically block all the signalling pathways leading to the differentiation of the other retinal cells in the eye. It is by uncovering this molecular process that Bernier was able to produce photoreceptors. More specifically, he has produced S-cones, which are photoreceptor prototypes that are found in the most primitive organisms and respond best to short wavelengths of light.

“Our method has the capacity to differentiate 80% of the stem cells into pure cones. Within 45 days, the cones that we allowed to grow towards confluence spontaneously formed organised retinal tissue that was 150 microns thick. This has never been achieved before.”

Although the research is in very early stages, the suggestion is that a new treatment for ARMD and other vision problems may be in the pipelines. Professor Bernier hopes that one day his method will be a cornerstone of visual medicine.

“Thanks to our simple and effective approach, any laboratory in the world will now be able to create masses of photoreceptors. Even if there’s a long way to go before launching clinical trials, this means, in theory, that will be eventually be able to treat countless patients.”

Read the original journal article here.

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