Human embryonic stem cell transplants found to improve vision in clinical trials
UCLA researchers are reporting a milestone in the therapeutic use of stem cells after two legally blind patients who received transplants of specialized retinal cells derived from human embryonic stem cells reported a modest improvement in their vision. Monitoring of the patients' progress over a four month period also found no safety concerns, signs of rejection or abnormal cell growth. The researchers are claiming that the success of the procedure could pave the way for a new therapy to treat eye diseases.
The patients underwent the outpatient transplantation surgeries in July, 2011, when both had relatively low doses of stem-cell-derived retinal pigment epithelial (RPE) cells transplanted into the space under their retinas. They subsequently received low-dose immunosuppression therapy for a number of weeks following the treatment.
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One patient was a woman in her 50s with Stargardt's macular dystrophy who went from only being able to discern hand movements to being able to see a single finger move. She also went from being unable to read any letters on a visual acuity letter-chart to being able to read five letters. Stargardt's disease causes progressive vision loss, usually starting when patients are between 10 to 20 years old.
Meanwhile, the other patient was a woman in her 70s with dry age-related macular degeneration who went from being able to read 21 letters on the chart to being able to read 33 letters a couple of weeks after the transplantation, before her reading stabilized at 28 letters. Dry age-related macular degeneration is the most common form of macular degeneration and the leading cause of blindness in the developed world.
There are no standard treatments for either Stargardt's disease or dry age-related macular degeneration, with both resulting in the deterioration and atrophying of the layer of retinal pigment epithelial cells located beneath the retina that support, protect and provide nutrition for light-sensitive photoreceptors in the eye.
Both patients are part of two separate clinical trials, each of which will eventually include 12 patients. The aim of the trials is to determine the safety of this particular use of stem cell therapy and the patients' ability to tolerate the treatment.
The authors of the preliminary report, which was published online on January 23 in the journal The Lancet, say that, "the ultimate therapeutic goal will be to treat patients earlier in the disease processes, potentially increasing the likelihood of photoreceptor and central visual rescue."