Los Angeles: Two legally blind women appeared to gain some vision after receiving an experimental treatment using embryonic stem cells, the scientists have reported.
While embryonic stem cells were first isolated more than a decade ago, most of the research has been done in lab animals.
The new results come from the first tests in humans for a vision problem. Researchers caution the work is still very preliminary.
"This study provides reason for encouragement, but plans to now get such a treatment would be premature," said stem cell expert Paul Knoepfler of the University of California, Davis, who had no role in the research.
Last summer, each patient was injected in one eye with cells derived from embryonic stem cells at the University of California, Los Angeles. One patient had the "dry" form of
age-related macular degeneration, the most common cause of blindness. The other had a rare disorder known as Stargardt disease that causes serious vision loss. There`s no cure for either eye problem.
After four months, both showed some improvement in reading progressively smaller letters on an eye chart. The Stargardt patient, a graphic artist in Los Angeles, went from seeing no letters at all to being able to read five of the largest letters.
However, experts said the improvement of the macular degeneration patient might be mostly psychological, because the vision in her untreated eye appeared to get better too.
Both patients remain legally blind despite their improvements, said experts not connected with the study.
"One must be very careful not to overinterpret the visual benefit," said Vanderbilt University retina specialist Dr. Paul Sternberg, who is also the president-elect of the
American Academy of Ophthalmology.
The findings were published online yesterday by the journal Lancet. This early test was meant to study whether the stem cell therapy was safe in people and not whether it would
Scientists at UCLA and Advanced Cell Technology, which funded the work, said they were pleased that there have been no signs of rejection or abnormal growth months after the procedure.