The report, published online in the medical journal The Lancet, is the first to describe the effect on patients of a therapy involving human embryonic stem cells.
The paper comes two months after Geron Corporation, a stem cell industry pioneer, cast a pall over the field by abruptly halting the world’s first clinical trial based on embryonic stem cells — one aimed at treating spinal cord injury. Geron, which has not published results from the aborted trial, also said it would abandon the entire stem cell field.
The results reported Monday could help lift some of that pall. They come from the second clinical trial involving the stem cells, using a therapy developed by the company Advanced Cell Technology to treat macular degeneration, a leading cause of blindness.
“It’s a big step forward for regenerative medicine,” said Dr. Steven D. Schwartz, a retina specialist at the University of California, Los Angeles, who treated the two patients.
Both patients, who were legally blind, told researchers that they had gains in eyesight that were meaningful for them. One said she could see colors better and was able to thread a needle and sew on a button for the first time in years. The other said she was able to navigate a shopping mall by herself.
Still, it is hard to judge much from only two patients, especially when there was no control group given a placebo treatment.
Indeed, Dr. Schwartz said that the improvement in vision of the woman who could go to the mall might have been a placebo effect, though he thought the improvement in the other patient did result from the implanted cells.
Yet another reason to be cautious is that Advanced Cell Technology has had a reputation for publicizing its positive work, in part because it has often been on the brink of insolvency.
The company’s stock was up 6 percent to 15 cents a share Monday.
Advanced Cell’s desire for publicity — its scientists are co-authors of the paper — could be one reason that the paper was published after only two patients out of a planned 24 were treated.
“It’s extremely unusual and it is contrary to my usual behavior,” Dr. Schwartz said of the early publication. But he said there was huge interest in the results. “I think it’s important for the field to have something positive,” he said.
Human embryonic stem cells can theoretically be turned into any type of cell in the body. Researchers envision one day making replacement cells and tissues for damaged organs, treating a wide range of diseases.
But the field has been controversial because the creation of the stem cells usually entails the destruction of human embryos.
In this case, researchers at Advanced Cell Technology turned embryonic stem cells into retinal pigment epithelial cells. Those cells help support the light detectors in the eye. Deterioration of these retinal cells can lead to damage to the macula, the central part of the retina, and to loss of the straight-ahead vision necessary to recognize faces, watch television or read.
Some 50,000 of the cells were implanted last July under the retinas in one eye of each woman in surgeries that took about 30 minutes.
One woman, Sue Freeman, who is in her 70s, suffered from the dry form of age-related macular degeneration, one of the leading causes of severe vision loss in the elderly.
The other, who asked that her name not be used to protect her privacy, was a 51-year-old graphic designer in Los Angeles with Stargardt’s macular dystrophy, which tends to occur in younger people.
There are no approved drugs for either disease.
One safety concern in using embryonic stem cells is that if any of the cells get into the body, they could form tumors. The researchers reported that this did not happen in the first four months after the surgery and that there were no obvious safety problems.
The women were given low doses of drugs to suppress the body’s immune system and prevent them from rejecting the implanted cells, even though the eye is somewhat shielded from the immune system.
Before the treatment, the woman with Stargardt’s was able to see the motion of a hand being waved in front of her but could not read any letters on an eye chart.
Twelve weeks after the treatment, she was able to read five of the biggest letters on the eye chart with the treated eye, corresponding to 20/800 vision, according to the paper.
“I kind of did have a day when I woke up and said there really is a difference here,” the woman said in an interview in late October, about three months after the surgery. “I want my other eye done.”
Ms. Freeman, who lives in Laguna Beach, Calif., went from being able to read 21 letters on an eye chart before treatment to 28 letters six weeks after treatment, an improvement to 20/320 from 20/500 vision, according to the paper.
However, vision in her untreated eye also improved somewhat, and Dr. Schwartz said that after a while he could not detect any evidence in her eye of the implanted cells, possibly because she stopped taking the drug to suppress her immune system, owing to side effects.
That is why, he said, he thought the effect might have been a placebo effect.
The trial is now continuing and expanding beyond U.C.L.A., and using gradually higher doses of cells. A patient with Stargardt’s was implanted in London on Friday.
Article source: http://feeds.nytimes.com/click.phdo?i=91d8d90d3b8f0c92e276752163a62463
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