How Safe are Embryonic Stem Cells?

November 12, 2012

How Safe are Embryonic Stem Cells?

The very first published clinical results of embryonic stem cells have already been published, wherein legally blind patients got injected in one eye to test the effects. The results show that they haven’t experienced any negative side effects. Plus, they seem to have better vision. These results may just be preliminary right now, but it still proves to be a vital milestone in the field of human embryonic stem cells (hESCs) overall.

The Discovery of hESCs

Human embryonic stem cells were first discovered 13 years ago and they have shown tremendous promise in treating diseases so far. However, they have been hounded by various ethical concerns and safety problems, as well, since the cell derivation usually ruins human embryos.

Current Clinical Trials

Current clinical trials that involve hESCs generally use cells known as retinal pigment epithelium, which are meant to sustain the light-sensing photoreceptors of the retina. These cells have been used on one eye of two elderly women – one with dry macular degeneration and another one with macular dystrophy. Four months post-treatment, these women hadn’t developed any growths or tumors nor have they shown signs of cell rejection or inflammation. The eyesight of both women appear to have improved, as well. Of course, measuring such small improvements in one’s vision is hard, in general, so there are no guarantees that these changes actually came about because of a placebo effect or because of the immune-suppressing drugs. Either way, though, it is definitely a huge milestone, which provides a lot of encouragement in the field and hope for a lot of families.

Clinical Trial Improvements

One trial is sponsored by Pfizer, the drug company, and involves slipping RPE cells derived from embryonic stem cells under the patient’s retina as opposed to injecting them into it. Since RPE cells create single cell layers by nature, it looks like this method would simply work better. A trial is already set to be conducted in the UK, wherein a dozen patients will be injected with different cell doses. Since the treatment seems safe, things are slowly accelerating and if things go well, younger patients might be able to benefit from the treatment in the long run, too.

The Safety of hESCs

Overall, the results of the use of embryonic stem cell treatment looks very good when it comes to macular degeneration. This is because the eyes are much less likely to experience an immune reaction compared to other parts of the body. Plus, animal studies seem to show that the RPE treatment is safe. Naturally, nobody will ever know until the clinical tests and the effectiveness of this treatment cannot be set in stone until the end of the trials with embryonic stem cells.


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