We're often talking on the Naked Scientists about research into stem cells, which could have the potential to treat many different ailments. This is because they can be persuaded to change into a wide range of cell types. Now researchers at the University of Washington in Seattle have used human embryonic stem cells to restore some sight, or at least light responses, to blind mice.
The researchers were using mice that were lacking a gene called Crx, which means they are blind from birth as they don't properly develop photoreceptors, the cells that sense light. They grew human embryonic stem cells in the lab, and treated them with certain chemicals and growth factors that encourage the stem cells to change towards being retinal cells - cells found at the back of the eyeball.
Then the scientists injected these modified stem cells into the eyeballs of mice. They found that the cells settled into the back of the eye, forming organised layers. And when the cells were injected into the eyes of the Crx-deficient mice, they started to turn into photoreceptors. When the scientists tested the mice's responses to light, they found that these new photoreceptors had some response to light flashes, compared with eyes that hadn't been injected, which showed no response to light at all. And the eyes with the biggest areas of transplanted cells had the biggest responses.
The researchers also tested transplanting the modified stem cells into albino mice, whose photoreceptors are very sensitive to light and break down. The stem cells also integrated into the retinas of these mice, and were more resistant to breaking down than the cells that were already there.
This is exciting because it suggests that human embryonic cells could be a good replacement for damaged photoreceptors, and maybe in the future could be used to restore sight to people whose eyesight is damaged, or even to those who have been born blind.
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