In theory, stem cells can turn into any type of human cell, meaning that they have the potential to treat a variety of diseases. What they can do in practice is another story: Because embryonic stem cell treatments usually require the destruction of human embryos, their potential has not been explored -- until now.
A new but tiny study, the first of embryonic stem cell treatment in humans, shows that they may hold promise for the treatment of eye diseases such as macular degeneration, a leading cause of blindness in the elderly.
Two legally blind women -- one suffering from macular degeneration, the other from Stargardt’s macular dystrophy, which can occur in middle age -- each received an implantation of 50,000 stem cells under the retina of one eye last July. They also received drugs to suppress their immune systems to keep the cells from being rejected.
Both patients reported improvements in sight. According to the New York Times,
One said she could see colors better and was able to thread a needle and sew on a button for the first time in years. The other said she was able to navigate a shopping mall by herself.
One of them was also able to several letters on an eye chart when she had previously been able to read none.
The experiment so far appears to have had no adverse side effects. One fear of stem cell treatments was that the cells could form tumors if they escaped into the body.
Dr. Steven D. Schwartz, a retina specialist at the University of California, Los Angeles, conducted the experiment using technology developed by Advanced Cell Technology; the results were published online in the journal The Lancet (pdf).
While it certainly is amazing to think that the treatment helped restore some vision to the blind (especially considering that there are no approved drugs for these diseases), there are a few important caveats.
First, the study was extremely small -- just two patients -- and there was no control group.
Additionally, while doctors did measure sight improvement in both patients, they caution that the progress they saw in one patient may have been due to the placebo effect.
For this patient, her sight improved from 20/500 to 20/320 six weeks after the surgery, but the doctor could not see the implanted cells in her eye after the first day, and the vision in her untreated eye also improved, even if only temporarily.
Implications for the field and next steps
Stem cell research has been on hold since 2001, when then-President George W. Bush prohibited federal funding of such research. President Barack Obama reversed that decision in 2009, but the field has suffered other setbacks.
Two months ago, Geron Corporation, a central player in stem cell research since the late 1990s, abruptly halted the world's first clinical trial using embryonic stem cells, plus announced that it would give up stem cells entirely as an area of research. The company cited lack of funding as the reason for its decision.
The researchers plan to do trials in 24 patients total, and The Independent reports that they will be recruiting patients with less advanced sight deterioration. For the initial study, they chose patients with advanced slight impairment in order to limit potential damage from the treatment.
While there's excitement that the treatment appears to have improved sight in the blind, the authors caution, "We are uncertain at this point whether any of the visual gains we have recorded were due to the transplanted cells, the use of immunosuppressive drugs, or a placebo effect."
Related on SmartPlanet:
- Biotech launches two stem cell trials for blindness
- FDA approves trial to use embryonic stem cells to treat macular degeneration
- Video: First 'chimera' monkeys created from multiple embryos
- First transfusion of lab-grown human blood succeeds
- Stem cell breakthrough could bring cure for genetic diseases
- Coming soon: $1,000 to map your genes
- Chinese medical school teaches genetics using Harry Potter
photo: retina (James Gallagher (ciotog)/Flickr)