Embryonic stem cells transplanted into eyes of blind restore sight

No effective treatments exist for either (AMD) or Stargardt's macular dystrophy, both of which can result in complete blindness caused by the loss of light-receiving photoreceptor cells in the retina.

The new treatment uses stem cells to recreate a type of cell in the retina that supports those photoreceptors.

Stem cells derived from embryos that are only a few days old have the ability to develop into any kind of tissue in the body.

By bathing the stem cells in a specially formulated cocktail of chemicals the scientists were able to stimulate them into turning into fully mature retinal pigment epithelium cells. They were then transplanted directly into the eyes of patients suffering from blindness.

Tests showed substantial improvement in 10 of 18 treated eyes. Eight patients were able to read more than 15 additional letters on a sight chart in their first year after treatment.

"Embryonic stem cells have the potential to become any cell type in the body, but transplantation has been complicated by problems including the risk of tumour formation and immune rejection, said Professor Robert Lanza, chief scientific officer at the US company Advanced Cell Technology, which funded the research.

"As a result, sites that do not produce a strong immune response, such as the eye, have become the first parts of the human body to benefit from this technology."

The transplants have proved controversial because they use stem cells derived from spare human embryos left over from IVF treatment.

But experts said the announcement showed that such therapies could bring real benefits.

Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, US, said: The work by Schwartz and colleagues is a major accomplishment, but the path to get to this point has not been smooth.

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Embryonic stem cells transplanted into eyes of blind restore sight