Stunning breakthrough makes blind mice see again

In what is being viewed as a major breakthrough scientists are facing the very real possibility of a cure for blindness.

A joint research project by scientists from the Institute of Ophthalmology and the Institute of Child Health in London, and the University of Michigan Medical School in the United States, has shown that destroyed retinas can be rebuilt and the sight of blind mice restored.

The breakthrough which has been described as "stunning", will mean that for the first time, doctors may be able to treat conditions that cause irreversible blindness, such as age-related macular degeneration (MD) and diabetic eye damage.

The researchers say that although much more work needs to be done, they believe the same can be achieved in human patients.

The researchers implanted immature "precursor" cells into the eyes of the mice which then developed into fully functioning photoreceptors.

Photoreceptors are specialized light sensitive cells that line the back of the eye and are essential for sight; in humans, destruction of these cells leads to eye diseases such as MD.

Precursor cells are similar to stem cells but have proceeded further along the path of development.

Previous attempts to achieve the same result using undifferentiated stem cells, which have not yet acquired a specific function, failed but those used in the mouse study had already been programmed to become photoreceptors, the pixel-like light-sensitive cells in the retina that make it possible to see.

The cells were extracted from newborn mice which were in the process of developing their eyesight.

The research suggests that human embryonic stem cells could also be coaxed to become photoreceptor precursors but the scientists believe it might be better to grow the precursors from adult stem cell-like cells found at the margins of the retina.

These could then be transplanted into patients.

The scientists believe that transplantations to treat eye disorders in humans may be only a decade away.

The findings of the study are published online by the journal Nature.