[AI] Stem Cells From Own Eyes Restore Vision To Blinded Patients, Study Shows

shahnaz shycurrim at yahoo.co.in
Fri Jun 25 04:30:40 EDT 2010

June 18 (Bloomberg) -- Patients blinded in one or both eyes by
chemical burns regained their vision after healthy stem cells were
extracted from their eyes and reimplanted, according to a report by
Italian researchers at a scientific meeting.

The tissue was drawn from the limbus, an area at the junction of the
cornea and white part of the eye. It was grown on a fibrous tissue,
then layered onto the damaged eyes. The cells grew into healthy
corneal tissue, transforming disfigured, opaque eyes into functioning
ones with normal appearance and color, said researchers led by
Graziella Pellegrini of the University of Modena’s Center for
Regenerative Medicine.

The stem-cell treatment restored sight to more than three- quarters of
the 112 patients treated, Pellegrini said yesterday in a presentation
at the International Society for Stem Cell Research meeting. The
patients were followed for an average of three years and some for as
long as a decade, Pellegrini said.

“The patients, they are happy, even the partial successes,” she said
in an interview at the meeting in San Francisco. “We have a couple of
patients who were blind in both eyes. Can you imagine for these
patients the change in their quality of life?”

The work was praised by Ivan Schwab, an ophthalmology professor and
stem cell researcher at the University of California, Davis, who has
treated patients in clinical trials with a procedure based on
Pellegrini’s work. While his patients improved for a time, the
benefits didn’t endure, he said in a June 15 telephone interview.
Pellegrini’s patients appear to have long-term improvement, he said.

“The powerful part of her work is she has such long-term follow-up,”
Schwab said.

Many of the patients she treated had been blind for years as result of
tissue and blood vessels growing over damaged parts of the eye. Some
had been through failed surgeries and alternative treatments.
Pellegrini estimated 1,000 to 2,000 patients in Europe suffer from
burns with chemicals such as bleach or industrial solvents and may
benefit from the procedure.

The key to success is to be certain that when the stem cells extracted
from the limbus are grown in culture they have the right mix of stem
cells and the differentiated cells that form the corneal tissue,
Pellegrini said. If there are too few stem cells in the transplant,
the improvement won’t last because there will be no reservoir to form
the new corneal cells needed with the normal recycling of cells over
time, she said.

The procedure succeeded after a single transplant in 69 percent of
cases. A second procedure was performed on some patients, boosting the
success rate to 77 percent, she said. The procedure was deemed a
partial success in 13 percent of cases and a failure in 10 percent,
she said.

Depending on the depth of the injury, some patients regained sight in
as little as two months, Pellegrini said. Others with deeper injuries
needed a second procedure and waited a year before sight was restored,
she said.

The applications of the work may extend to other organs, Schwab said.

“This is bigger than just the surface of the eye,” he said. “She may
be making a model for how to regenerate livers or other organs.”

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