Jan 24 2012

Stem Cells for Blindness

File this one under “encouraging but preliminary.” Published in The Lancet – researchers report the results of two patients with two different forms of macular degeneration (the most common cause of blindness in the developed world) who had stem cells injected into one eye. Both patients reports improved vision. This study is the first to report a clinical benefit from the use of embryonic stem cells (other kinds of stem cells, like bone marrow, have been used for a long time).

The study, however, is a very preliminary study designed mostly to look at safety. There are concerns that injecting stem cells into the eye, or anywhere, might result in tumor formation. In these two patients the stem cells survived well as retinal pigment epithelium cells. They did not form any tumors, grow uncontrollably, show signs of rejection or other negative effects as far as could be seen. This is just two patients, however, so any statements about safety have to be very cautious.

What surprised the researchers is that both patients also reports improved vision. In one patient there was clear improvement in visual acuity (from hand waving to 20/800). In the second patient there were more subtle signs of improved vision, but also in the untreated eye leading researchers to believe this was likely due to placebo effects.

While encouraging, the researchers are careful to express caution in interpreting these results. These are just two patients, and the benefits are mild (although significant in terms of functionality for the one patient with clear improvement). It is simply too early with too few patients to reach any firm conclusions. Further the study once again shows the power of deception in these studies – even something that might seem as objective as visual acuity is subject to placebo effects.

It is always instructive to contrast the very sober and cautious tone of legitimate science-based researchers with those of dubious practitioners. Even in the face of  a potential breakthrough treatment, they are emphasizing uncertainty and the preliminary nature of these results. They are considering all the possible sources of error and deception, not looking for reasons to dismiss criticism.  They are downplaying the results, not exaggerating them.

It is also important to emphasize that at present there are no legitimate embryonic stem cell (or equivalent) treatments for things like blindness. These types of treatments are still experimental. There are many clinics around the world, however, that are exploiting hype to offer bogus stem cell treatments for a long list of diseases and at massive price tags. These are fraudulent clinics who are taking advantage of desperate patients. I hope that the renewed interest spawned by this study does not drive more patients into the jaws of these sharks.

It will likely still be 5 or more years before stem cell treatments for macular degeneration become available outside of a clinical trial, and that is if everything goes well. I think we very likely will see the day where this type of blindness will be effectively treated by stem cells, but we have to go through the tedious process of science. It exists for a reason.

5 responses so far

5 Responses to “Stem Cells for Blindness”

  1. BillyJoe7on 24 Jan 2012 at 3:32 pm

    This is how the ABC treated this story;


    A reporter interviewed Martin Pera, professor of Stem Cell Sciences at the University of Melbourne. It’s not bad except for the fact that the professor failed to mention that the “improvement” in the second patient was most likely due to placebo (because the vision in the intreated eye “improved” also).

  2. starskepticon 25 Jan 2012 at 5:35 am

    “due to placebo”
    …in other words – the placebo did nothing and this particular case “improved” on its own…

  3. daedalus2uon 25 Jan 2012 at 11:43 am

    In the eye there are some good ways (but indirect and non-standard) to test for basal nitric oxide levels. The vessels in the retina can be imaged in real time. These vessels respond to changes in light levels by dilating or contracting. How fast those vessels respond to changes in light levels is an indication of background NO levels.

    Most of the retinal degenerative disorders are vascular in nature and are associated with other vascular disorders, hypertension, obesity, diabetes. Often these are secondary to low nitric oxide levels, for example tortuous retinal vessels is (to me) a classic sign of low NO causing flow mediated morphological changes in vessel anatomy due to normal vascular remodeling.

    These are the same types of changes that occur in other tissue compartments, for example capillary rarefaction is commonly observed in diabetes, hypertension, vascular dementia, etc.

    A common treatment for some types of retinopathy is to reduce the number of retinal cells by killing some via laser ablation. My hypothesis is that this reduces metabolic load to what the rarefacted retinal vasculature can support, so vision is improved even though there are fewer cells.

    Since the physiological placebo effect is mediated through nitric oxide, a placebo effect would very likely lead to improved vision.

    Stem cells might also generate NO, they might also trigger immune system interactions and inflammation which triggers NO and angiogenesis.

    What would be an interesting test would be to put a reporter system that is activated by cGMP (which is activated by NO) into the stem cells that are being used, like in this work (which was not in stem cells).


    You couldn’t really do this in humans, unless maybe you tied it to something so it would default to “off” (maybe not even then). Then you could image where the NO levels are, and how various treatments affect them.

  4. Marshallon 25 Jan 2012 at 4:35 pm

    I’m wondering if we can really isolate this as placebo. Regions of cortex that receive jumbled/signal-free information more or less stop working and might become co-adopted by other nearby networks. Couldn’t it be possible that the increased acuity in one eye “jump-started’ some of the binocular cells in V1 that receive inputs from both eyes, and that had previously been “sleeping” so to speak, leading to increased visual acuity in both?

  5. willradikon 26 Jan 2012 at 12:40 am

    Is it feasible that a technique to regenerate damaged optic nerve tissue (such as that from glaucoma) might be developed from stem cells at some time? Or does the optic nerve present any special challenges that would make it less possible than the application you describe above?

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