Stem cell therapy success in treatment of sight loss from macular degeneration

This UCL photo shows an eye diseased with age-related macular degeneration, the leading cause of blindness among the elderly in the developed world. Photograph: UCL/PA

Patients with a devastating eye disease who had embryonic stem cell therapy to improve their sight have suffered no major side-effects since they had the treatment, scientists report.

The study (pdf) represents the first evidence for the long-term safety of the pioneering therapy, which restored some vision to more than half of the patients who took part in the trial.

There had been concerns that the cells could be rejected by the bodys immune system or become overactive and grow into tumours. But after following the patients for up to three years, researchers said the treatment appeared to be safe.

The trial focused on 18 patients with two different types of macular degeneration. The diseases have no effective treatments and are among the leading causes of blindness in adults and children in the developed world.

Nine patients with Stargardts macular dystrophy and nine with dry atrophic age-related macular degeneration had injections of 50,000 to 150,000 retinal pigment cells behind the retina of their worst-affected eye. The pigment cells were created in the lab by treating human embryonic stem cells (hESCs) with chemicals that make them transform into retinal cells.

The vision of most patients improved after transplantation of the cells. Overall, the vision of the patients improved by about three lines on the standard visual acuity chart, whereas the untreated fellow eyes did not show similar improvements in visual acuity. The patients also reported notable improvements in their general and peripheral vision, as well as in near and distance activities, said Robert Lanza, chief scientific officer of Advanced Cell Technology, which funded the research.

One of the patients, a 75-year-old horse rancher from Kansas, was blind in the eye he had treated. A month after the therapy, his vision had improved by 10 lines and he had taken to riding horses again. Other patients could use their computers or read a watch, Lanza said.

Little things like that which we all take for granted have made a huge difference in the quality of their life. Indeed, one patient recently went to the mall for the first time, and another patient can travel to the airport by herself, he added.

Writing in The Lancet, the scientists said that patients had tolerated the implanted cells for up to 37 months. They found no evidence of hyper-proliferation or rejection of the cells during a typical follow-up period of 22 months.

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Stem cell therapy success in treatment of sight loss from macular degeneration