Stem Cells for Macular Degeneration

One of the most difficult things in health care, both for patients and doctors, is dealing with diseases and conditions that have no treatment. The most common condition like this that I encounter is dry macular degeneration.

Last week The Lancet published a preliminary report from 2 studies using human embryonic stem cells (hESCs) for treatment of macular degeneration.  The studies, from Steven Schwartz at UCLA’s Jules Stein Eye Institute, are funded and partially run by a private company, Advanced Cell Technology. They are the first human trials using transplanted hESCs for macular disease.

Stem cells are cells that have the ability to replicate and produce more stem cells, and have the ability to develop (or differentiate) into specialized types of cells. Stem cells can be found in embryos (human embryonic stem cells or hESCs), as well as adult bodies (somatic stem cells eg in bone marrow and umbilical blood). hESCs are more potent, in other words they are able to turn into a wider variety of specialized cells, which is why much research has been focussed on finding clinical applications for them.

In these studies stem cells were turned into retinal pigment epithelial (RPE) cells and then transplanted by injection into the patient’s eyes, under the retina, during a surgical procedure. Two patients have been treated so far. One patient has dry macular degeneration, the other has Stargardt Disease. In both patients the cells survived and persisted, there were no complications, and in one patient vision may have improved. 

The main barriers to the use of hESCs are concerns about safety (the potential for teratoma formation, abnormal cell growth and rejection), and ethics (hESCs are derived from human embryos). This report is part of a series of trials to assess whether the technology is safe, and what treatment effect may be possible. So far the fact the stem cells can survive in the eye without causing problems makes the results very promising.

But apart from ethical concerns regarding the origin of hESCs, there is reason to question partial reporting of such preliminary results. This report is very early. Results from only 2 patients were reported, and according to ClinicalTrials.gov both these studies are still recruiting patients. The findings were reported on Tuesday, the day after their online publication, in the Business section of The New York Times, which also reported a 23% rise in Advanced Cell Technology’s share price. Although the investigators from UCLA declared no conflict of interest and retained full responsibility for the decision to publish the findings, the study’s sponsors were involved in every other aspect of the study. Is it possible that commercial considerations play a role in the decision to release very early data?

Nevertheless the study is ongoing, and these early results are very exciting, giving patients, families and doctors affected by these conditions reason to be hopeful. 

The Australian campaign has obviously been very effective. The graphic photo of an eye with lids held apart with a speculum brings the message home, although the damage smoking does lies deeper, unseen in the photo, and half of Australia’s smokers still haven’t got the message.

Smoking is associated with a wide variety of eye diseases, both directly and through increasing the effects of a patient’s genetic susceptibility. The most important of these is macular degeneration (AMD). Smokers have 4 times the risk of non-smokers of developing the disease, and a smoker’s “second-hand” smoke increases the risk of family members developing AMD. There are a number of reasons for the increase in risk. Nicotine itself has been shown to cause over-expression of VEGF, a protein that stimulates new blood vessel proliferation, and has been shown to block PEDF, a protein that suppresses abnormal blood vessel proliferation. The proliferation of abnormal “new” blood vessels is what leads to the aggressive “wet” form of AMD. Tobacco smoke also reduces anti-oxidants, reducing the capacity of the macula to respond to toxic and other damage.

Cigarette smoke increases the risk of cataract development, dry eye syndrome, visual loss from thyroid eye disease, and recent studies have shown that it increases the risk and severity of ocular inflammation.

We need to encourage our smoking patients to quit for the sake of their eyesight, and support them when they try. The Federal government is currently fighting “big tobacco” in the high court, trying to get plain packaging through. Tobacco companies are worried about the loss of their brand identity. But to your eye, all cigarettes are branded the same.

Article: Steven D Schwartz et al. Embryonic stem cell trials for macular degeneration: a preliminary report, The Lancet, Available online 24 January 2012, ISSN 0140-6736, 10.1016/S0140-6736(12)60028-2. 

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