A review in the journal Expert Opinion on Biological Therapy (http://dx.doi.org/10.1517/14712598.2016.1093110) has highlighted the existence of almost 20 clinical trials, either completed or on-going, in the field of retinal degenerative stem cell treatment. The review points out that considerable progress made in the scientific field has directly led to a number of human studies on potential treatments for age-related macular degeneration, retinitis pigmentosa and Stargardt’s disease. The author of the study, Prof. Henry Klassen, a long time research expert and innovator with both academic and commercial interests in stem cell therapies, argues that, “we now stand at what may, in retrospect, be seen as a historic inflection point in the progress towards effective regenerative clinical treatments for neurodegenerative diseases.”
While there are indeed several encouraging reports and advances in the development of stem cell technologies into viable therapeutics, no such products have yet being approved for the treatment of any ophthalmic disorders. However, the field is still in its infancy and even a cursory search within the US clinicaltrials.gov database shows that there are several thousand studies appearing under the search term “stem cell”, while close to 150 results are listed for the search string of “stem cell” + “eye”. Prof. Klassen however lists 18 studies that use cell-based therapeutics in the retina and are registered with the FDA or Japanese Ministry of Health. The studies include eight (8) trials in AMD, seven (7) in retinitis pigmentosa, two (2) in Stargardt’s disease and one (1) in retinal vascular occlusion.
The review additionally highlights the two broad divisions into which current stem cell therapies may be categorized, namely the use of fetal neural progenitor cells (NPCs) and the generation of RPE cells from pluripotent stem cells. Advanced Cell Technology, now known as Ocata Therapeutics, is one of the pioneers in the field, responsible for the first US FDA approved tests of a human embryonic stem cell product in 2011. The study remains on-going but is no longer recruiting patients. However, several other studies provide an encouraging snapshot of the technologies and conditions under investigation. Autologous induced pluripotent stem cell-derived RPE are under investigation for the treatment of exudative AMD in the RIKEN centre in Japan while allogenic foetal derived neural stem cells are being tested by Stem Cell Inc., in the US for the treatment of the atrophic form of AMD. A number of other studies including the use of bone marrow derived cells and umbilical tissue derived cells are also underway in both North and South America. While the jury remains out on the eventual clinical value of these new products, Prof. Klassen concludes that, ”only time will tell if the cell products now being tested can reliably demonstrate clinically significant levels of efficacy in the relevant patient populations.”