For low vision specialists and those who consult them
Crystal ball gazing: gene therapy, stem cells or retinal prostheses?
October 20, 2009Posted by on
There is a nice trio of papers in the current issue of the journal Eye which review the current state of research in gene therapy, stem cell therapy, and retinal prostheses. They are all well written and offer a balanced view of the likelihood of each of these techniques being useful for people with retinal disease.
The gene therapy paper, by Jim Bainbridge of the Moorfields/UCL Institute of Ophthalmology centre, summarises the principles behind gene therapy and briefly describes the results of the Moorfields, University of Pennsylvania and Childrens Hospital of Philadelphia trials. These trials were all for people with a rare but well understood degeneration called Leber’s Congenital Amaurosis. Each of the groups report improvement on some measures of function, although not visual acuity. Bainbridge suggests that the treatment will be most effective when applied very early in the disease process when there are still a large number of cells which can be “rescued”. He also claims it will be easier to treat diseases which affect the retinal pigment epithelium than the photoreceptors, so for example Stargardt disease will be less easy to treat with this technique.
The stem cell paper is by Johnson and colleagues from Cambridge. They describe some of their laboratory work on animals with induced glaucoma. Whilst these results are encouraging there are many technical issues which need to be addressed, which they discuss. Of course there are also very large ethical and regulatory issues with stem cell therapy, particularly for embryonically derived stem cells.
The final paper summarises some of the work on retinal prosthesis (“artificial retinas” implanted into people with no vision from diseases such as retinitis pigmentosa. There are several different technologies which are described in this paper, and the authors state that three different commercial products are likely to appear by the end of 2010 (from Second Sight, Intelligent Medical Implants and from Retina Implant). They also describe a very interesting approach used by a group at Imperial College, London, where viral engineering can make retinal ganglion cells or bipolar cells light sensitive (i.e. which can make nerve cells act like photoreceptors). This sounds very exciting, although no in vivo animal trials of this technology have yet been performed, let alone human trials.
Together the three articles provide an interesting overview of cutting edge science at present. I imagine that in the next 5-10 years all of these methods will be used more and more for people with eye disease. I wouldn’t like to guess which will end up being the most successful approach, but think we should all watch these emerging fields of science with interest.