Canadian researchers say they have made huge strides in potentially reversing the effects of age-related macular degeneration (AMRD) by transplanting stem cells.
ARMD is a common eye problem caused by the loss of cones. A team of researchers at the University of Montreal has developed a highly effective in vitro technique for producing light sensitive retina cells from human embryonic stem cells.
“Our method has the capacity to differentiate 80% of the stem cells into pure cones,” said Gilbert Bernier, a University of Montreal professor and study author. “Within 45 days, the cones that we allowed to grow towards confluence spontaneously formed organized retinal tissue that was 150 microns thick. This has never been achieved before.”
ARMD is caused by the degeneration of the macula, which is the central part of the retina that is key to eyesight. The degeneration is caused by the destruction of the cones and cells in the retinal pigment epithelium (RPE), a tissue that is responsible for the reparation of the visual cells in the retina and for the elimination of cells that are too worn out.
Currently there is no cure for ARMD because humans are born with a fixed number of cones; there is currently no natural way for their replacement. As we age, the RPE’s maintenance is less and less effective – waste accumulates, forming deposits.
Bernier's research provides new hope. In order to verify the technique, Bernier injected clusters of retinal cells into the eyes of healthy mice. The transplanted photoreceptors migrated naturally within the retina of their host.
“Cone transplant represents a therapeutic solution for retinal pathologies caused by the degeneration of photoreceptor cells,” Bernier explained. “To date, it has been difficult to obtain great quantities of human cones.”
May lead to new treatments
Bernier believes his discovery offers a way to overcome this problem. From it, new treatments may be developed for currently non-curable degenerative diseases, like Stargardt disease and ARMD.
“Researchers have been trying to achieve this kind of trial for years,” he said. “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 [sic] able to treat countless patients.”
According to the National Institutes of Health (NIH), ARMD is most common in people over age 50 and is the leading cause of vision impairment among that age group. In some people, ARMD advances so slowly that vision loss does not occur for a long time. It can also progress quickly, leading to a loss of vision in one or both eyes.
As AMD progresses, a blurred area near the center of vision is a common symptom. Over time, the blurred area may grow larger or you may develop blank spots in your central vision. Objects also may not appear to be as bright as they used to be.
The Canadian findings may be particularly significant because people are living longer. That extended lifespan increases the likelihood of developing ARMD.