Paralyzed Mice Move Again With Stem-Cell Therapy

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Paralyzed Mice Move Again With Stem-Cell Therapy

http://www.medicalnewstoday.com/healthnews.php?newsid=45641

Embryonic stem cells have been used to restore limb movement in

paralyzed mice, say scientists at s Hopkins University School of

Medicine, USA. The embryonic stem cells formed new nerve connections

in the paralyzed mice.

This research is seen as proof by scientists that one day paralyzed

humans will be cured as a result of stem-cell grafts. It may be

several years away, but the evidence that it will come is much more

compelling now.

The difference between this experiment and others is that this one

has managed to get the neurons to make functional connections to

muscle. Previous studies managed to use stem cell therapy to create

nerve cells only.

For a limb muscle to move, a brain cell must send a message to a

motor neuron, which lies in the spinal cord. The motor neuron in the

spinal cord then reaches out to the muscle using axons, long fibers.

An impulse is sent down the axons and the muscle contracts. The

message relay is done through a complicated system of signalling

chemicals.

Dr. Kerr, lead researcher, and his team, devised a neural

concoction that lead to the creation of a network of new motor

neurons that could restore the brain's ability to get its message all

the way through to the limb muscles.

The scientists got the mouse embryonic stem cells to turn into motor

neurons. By adding retinoic acid and sonic hedgehog protein, they

managed to get the new motor neurons to exist happily in the spinal

cord. They were then delivered into the spinal chords of paralyzed

mice.

Naomi Kleitman, U.S. National Institute of Neurological Disorders and

Stroke, who helped fund the study, said " We know that there are

proteins in this area that inhibit axons from growing in adult

animals. They're part of how we keep our nervous system from going

haywire during normal function. " The scientists had to find a way of

preventing this stopping of axons from growing. By adding cyclic AMP

and rolipram the scientists were able to stop the body from blocking

the growth of axons.

They then managed to get the right axons to grow in the way they

wanted by using chemicals which acted like axon growth traffic

lights.

In one mouse, 4,100 new motor neurons were created in the spinal

cord. Of those, 200 left the cord, of which 120 reached the skeletal

muscle. The scientists say the new connections look identical to the

ones seen in healthy mice.

Of the 15 paralyzed mice, 11 regained muscle function and strength.

Researchers say further studies are needed, but stressed that this is

probably the beginning of something which one day may help paralyzed

humans move again.