[THS] Stem Cells From Own Eyes Restore Vision to Blinded Patients

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http://www.bloomberg.com/apps/news?pid=20601124&sid=agH9jKT0ksHY

Stem Cells From Own Eyes Restore Vision to Blinded Patients

By Rob Waters

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.

‘Long-Term’ Effect

“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.

Success Rate

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.”

To contact the reporter on this story: Rob Waters in San Francisco at
rwaters5 at bloomberg.net.