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Stem Cells Show Promise as Cataract and Blindness Treatments

The best treatment options for cataracts and corneal blindness today involve possibly risky surgical implants, but new research may point to the growing potential for less-invasive stem-cell therapies.

An international team of scientists, led by researchers at the University of California San Diego, successfully treated cataracts in 12 human infants by employing their stem cells to heal the eye, according to a paper published online on Wednesday in the scientific journal Nature.

In a separate study also published in Nature, researchers from Japan and the U.K. treated corneal blindness in six rabbits with lab-grown stem cells, which they said may one day reduce the need for corneal transplants with donated tissues.

Successful results in animals often can’t be replicated in humans, but researchers nonetheless said they found both studies encouraging. James Tsai, president of the New York Eye and Ear Infirmary of Mount Sinai, who wasn’t involved with the two studies, said the techniques illustrated the possibilities for stem-cell therapies for which physicians have been hoping. “This is something that we always thought was possible,” he said.

More than 20 million people around the world suffer from cataracts, which cloud the eye’s lens, a transparent structure that focuses light on the retina.

Surgery to insert artificial replacement lenses can help restore sight. But the procedure can also damage cells around the insertion site, said Kang Zhang, professor of ophthalmology and chief of ophthalmic genetics at UC San Diego, who helped lead the first study.

Most cataract sufferers are elderly adults, but Dr. Zhang and his colleagues conducted their study in 12 human infants born with congenital cataracts, whose developing eyes didn’t take well to artificial replacement lenses.

New research may point to the growing potential for less-invasive stem-cell therapies for cataracts and corneal blindness. PHOTO: GETTY IMAGES

The researchers made a relatively small incision in the infants’ eyes and removed the damaged lenses, which allowed stem cells present in the infants’ eyes to generate a new lens. The team had previously found stem cells, called LECs, expressed certain genes that could let them develop into lens-like cells.

After surgery in each infant, transparent lenses grew in both eyes and the small incision healed within three months. The team observed fewer side effects in the 12 infants compared to a control group that underwent the artificial lens implants, which requires a larger incision.

“That’s the beauty of it,” Dr. Zhang said. “If we can use our own dormant stem cells and trick them to regrow the entire organ, it will be much less invasive.”

Dr. Tsai of Mount Sinai said further research is needed to test whether the procedure would work in older patients.

In the second study, researchers from Japan and Britain used human stem cells to treat corneal blindness in rabbits. The condition affects millions of people worldwide and develops after damage to the cornea.

The scientists, from Osaka University and Cardiff University, started with human cells that had been engineered back into stem cells, a type of cell known as an induced pluripotent stem cell. They cultured these cells in a lab until the cells developed into different types of ocular cells, including retinal and corneal cells.

The scientists then cultivated the corneal cells into sheets of tissue, and transplanted them into the eyes of the rabbits. The procedure restored the animals’ visual function “with no significant complications,” one of the researchers, Kohji Nishida, professor and chairman of the department of ophthalmology at Osaka University Medical School, said by email.