An important factor in the speed of development, cost, and availability of future stem cell therapies is the existence of an efficient, reliable way to create large numbers of the specific cell types needed. This is one of the main limiting factors for many areas of medical development in cell-based regenerative medicine. Here, researchers establish a methodology for generation of photoreceptor cells that could be used to rebuild retinal tissue, which is good news for progress towards regenerative therapies for conditions such as macular degeneration:
Age-related macular degeneration (ARMD) is due to the degeneration of the macula, which is the central part of the retina that enables the majority of eyesight. This 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. However, there is only so much reparation that can be done as we are born with a fixed number of cones. They therefore cannot naturally be replaced. Moreover, as we age, the RPE's maintenance is less and less effective - waste accumulates, forming deposits.
A research team 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. 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."
In order to verify the technique, researchers 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. To date, it has been difficult to obtain great quantities of human cones." The discovery offers a way to overcome this problem, offering hope that 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. 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."