Scientists Help Blind Mice See

[DirtBag Andy]

A cell transplant is a light at the end of the tunnel.
November 9, 2006
As the old nursery rhyme goes, chasing the farmer’s wife didn’t turn out so well for the three blind mice. Lucky for them, a new discovery has shown that blind mice can see again—and someday, maybe blind humans will, too.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Scientists from the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-comffice:smarttags" /><st1lace w:st="on"><st1:PlaceType w:st="on">University</st1:PlaceType> of <st1:PlaceName w:st="on">Michigan</st1:PlaceName></st1lace> and the University College London used immature cells from the retinas of baby mice to create functioning cells in the retinas of blind adult mice. They found that when the photoreceptors—cells that capture light—were taken from newborn mice and transplanted to the retina of the adult mice, the retinal function of the adults was partially restored. <o></o>
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Dr. Anand Swaroop, a scientist at the <st1lace w:st="on"><st1:PlaceType w:st="on">University</st1:PlaceType> of <st1:PlaceName w:st="on">Michigan</st1:PlaceName></st1lace> and one of the principal investigators for the study, explains that photoreceptors come in two shapes: rods and cones. “I compare them to queen bees and soldiers—rods are like bees, and the soldiers are trying to protect them,” he says. Although highly-sensitive rods only make up a small percentage of human photoreceptors, they are critical for night vision. They are also the cells that die first and cause blindness when a person has macular degeneration. <o></o>

The key to this development, Dr. Swaroop explains, was catching the photoreceptors at an intermediate stage of development, before they actually became rods. A few years ago, he and his team discovered the regulatory gene that makes photoreceptors that are slated to become rods actually develop into rods. Rather than putting neural stem cells in the retina and hoping they would grow into rods, they decided to use their knowledge about the gene in order to locate the “precursor” rods in newborns and transplant them into the blind mice. <o></o>
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Even in the degenerated retinas of the blind mice, the new cells were able to grow into rods and survive. “What our studies show is that it is the state of the donor cell that is more important than the state of the recipient cell,” Dr. Swaroop says. While the behavioral function of the mice has not yet been measured, their retinas did begin to function again. <o></o>
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Now, scientists hope the same work can be done for humans by developing rod cells from embryonic stem cells or adult stem cells—after all, taking eye cells from newborn babies probably wouldn’t go over well. The problem now, says Dr. Swaroop, is learning how to identify these “precursor” rod cells in humans. They have found several different “markers” on the surfaces of the cells that can help them to be identified, and are now examining the markers further.<o></o>
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“I think that [our discovery] will give a new direction for stem cell research,” says Dr. Swaroop. “Most people have been trying to use stem cells directly for therapeutic purposes and hoping they will make the kind of cells you want. Hopefully our research will tell people that it may be a good idea for us to push stem cells into a specific type before we use them for therapeutic purposes.”<o></o>
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He adds, “It tells us the potential that these stem cells have. A lot more work is ahead of us. You can see the light at the end of [the tunnel], but the tunnel is still long.”
http://www.redherring.com/Article.as...or=Biosciences
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