A spinal cord injury often leads to permanent paralysis and loss ofsensation below the site of the injury because the damaged nerve fiberscan't regenerate. The nerve fibers or axons have the capacity to growagain, but don’t because they're blocked by scar tissue that developsaround the injury.

Northwestern University researchers have shown that a new nano-engineered gel inhibits the formation of scartissue at the injury site and enables the severed spinal cord fibers toregenerate and grow. The gel is injected as a liquid into the spinalcord and self -assembles into a scaffold that supports the new nervefibers as they grow up and down the spinal cord, penetrating the siteof the injury.

When the gel was injected into mice with a spinal cord injury, after six weeks the animals had a greatly enhanced abilityto use their hind legs and walk.

The research is published today in the April 2 issue of the Journal of Neuroscience.

"We are very excited about this," said lead author John Kessler, M.D.,Davee Professor of Stem Cell Biology at Northwestern University'sFeinberg School of Medicine. "We can inject this without damaging thetissue. It has great potential for treating human beings.

"Kessler stressed caution, however, in interpreting the results. "It's importantto understand that something that works in mice will not necessarilywork in human beings. At this point in time we have no informationabout whether this would work in human beings."

"There is no magic bullet or one single thing that solves the spinal cord injury,but this gives us a brand new technology to be able to think abouttreating this disorder," said Kessler, also the chair of the DaveeDepartment of Neurology at the Feinberg School. "It could be used incombination with other technologies including stem cells, drugs orother kinds of interventions."

“We designed our self-assembling nanostructures -- the building blocks of the gel -- to promote neurongrowth,” said co-author Samuel I. Stupp, Board of Trustees Professor ofMaterials Science and Engineering, Chemistry, and Medicine and directorof Northwestern’s Institute for BioNanotechnology in Medicine. “Toactually see the regeneration of axons in the spinal cord after injuryis a fascinating outcome.

”The nano-engineered gel works in several ways to support the regeneration of spinal cord nerve fibers.In addition to reducing the formation of scar tissue, it also instructsthe stem cells --which would normally form scar tissue -- to instead toproduce a helpful new cell that makes myelin. Myelin is a substancethat sheaths the axons of the spinal cord to permit the rapidtransmission of nerve impulses.

The gel's scaffolding also supports the growth of the axons in two critical directions -- up thespinal cord to the brain (the sensory axons) and down to the legs (themotor axons.) "Not everybody realizes you have to grow the fibers upthe spinal cord so you can feel where the floor is. If you can't feelwhere the floor is with your feet, you can't walk," Kessler said.

Now Northwestern researchers are working on developing the nano-engineeredgel to be acceptable as a pharmaceutical for the Food & DrugAdministration.

If the gel is approved for humans, a clinical trial could begin in several years.

"It's a long way from helping a rodent to walk again and helping a humanbeing walk again," Kessler stressed again. "People should never losesight of that. But this is still exciting because it gives us a newtechnology for treating spinal cord injury."
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Dr Vishnu Kiran Manam

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