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.