Previous research has shown that the injection of stem cells can help
bridge a damaged spinal cord that was blocking nerve cells from
delivering their movement messages to the muscles. Now it appears the
therapy that combines differentiated stem cells with myelin inhibitors
and a motor axon tropic factor helped paralyzed rats restore functional
motor units and gain some physical recovery.
Scientists' ability to differentiate stem cells toward specific mature
cell lineages is assisting in the study of diseases and the development
of new treatments. Embryonic stem cells can be induced to create normal
pathways for the generation of spinal motor neurons, and this activity
can be encouraged by certain pharmacologic agents.
Based on this hypothesis, researchers led by Douglas Kerr, M.D., Ph.D.
of explored different strategies to restore motor function in paralyzed
rats. They used agents to inhibit myelin-mediated axon repulsion and
others to provide attractive cues within peripheral nerves. They hoped
to stimulate the formation of functional muscular units.
The researchers began by inducing embryonic stem cells from rats to
“differentiate into motor neurons.” They divided the rats into 8
groups. Some of the rats received neurons that had been treated to
potentially increase their survival and their ability to extend axons.
Some groups received injections of Rolipram and dibutyrl cAMP to
potentially neutralize the inhibitory effects of myelin on axon
outgrowth. And some groups received a motor axon tropic factor, GDNF, to
potentially attract transplanted axons toward skeletal muscle targets.
They then examined innervation of host skeletal muscle,
electrophysiologic evidence of functioning motor units and signs of
recovery from hind limb paralysis.
GDNF acts as a focal attractive cue for embryonic stem cell-derived
motor axons. The rats with bcAMP and Rolipram injections established
neuromuscular junctions between transplant and host, resulting in
noticeable recovery.
The researchers point out that "Animals transplanted with inhibitors of
myelin and GDNF within the peripheral nervous system formed
approximately 125 new connections with host skeletal muscle, 50 of which
were electrically active in the distal hind limb. We also provide
several lines of evidence that strongly suggest that this functional
innervation was required for the behavioral recovery observed."
The goal is to transfer what they have learned with rats to higher
mammals and then to humans. The research is published in the July issue
of Annals of Neurology, a journal published by John Wiley & Sons. The
article is also available online via Wiley Interscience (www.interscience.wiley.com/journal/ana).
Dan Wilson
Best Syndication
Books about Pain
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