Cancer Drug Aids Regeneration of Spinal Cord After Injuries

ScienceDaily (Jan. 28, 2011) — After a spinal cord injury a number of factors impede the regeneration of nerve cells. Two of the most important of these factors are the destabilization of the cytoskeleton and the development of scar tissue. While the former prevents regrowth of cells, the latter creates a barrier for severed nerve cells. Scientists of the Max Planck Institute of Neurobiology in Martinsried and their colleagues from the Kennedy Krieger Institute and University of Miami in the United States, and the University of Utrecht in the Netherlands, have now shown that the cancer drug Taxol reduces both regeneration obstacles.Paraplegia. This is often the long-lasting result, when nerve fibers have been crushed or cut in the spinal cord. In contrast, for example, to the nerves in a cut finger, the injured nerve cells in the central nervous system (CNS) won't regrow. Scientists have been working for decades to discover the reasons for this discrepancy in the regeneration abilities of nerve cells. They have found a variety of factors that prevent the regeneration of CNS nerve cells. One by one a number of substances that act like stop signs and halt the resumption of growth have been discovered. Other obstacles lie within the cells: The microtubules, small protein tubes which compose the cells' cytoskeleton, are completely jumbled in an injured CNS nerve cell. A structured growth becomes impossible. In addition to this, the lost tissue is progressively replaced by scar tissue creating a barrier for growing nerve cells.

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How Injured Nerves Grow Themselves Back

ScienceDaily (Oct. 3, 2010) — "Unlike nerves of the spinal cord, the peripheral nerves that connect our limbs and organs to the central nervous system have an astonishing ability to regenerate themselves after injury. Now, a new report in the October 1st issue of Cell, a Cell Press publication, offers new insight into how that healing process works.
"We know a lot about how various cell types differentiate during development, but after a serious injury like an amputation, nerves must re-grow," said Allison Lloyd of University College London. "They need a new mechanism to do that because the developmental signals aren't there."
That kind of regrowth isn't easy to pull off. Peripheral nerves are long cells; their nucleus is in the spinal cord and the axons that extend from them and relay nerve messages can reach all the way down a leg. "When a nerve gets cut, all the axons downstream degenerate," Lloyd said. Regrowth requires that the two ends somehow find their way back to each other through damaged tissue.
Scientists knew that Schwann cells were important to that process. Those cells are found wrapped around axons, where under normal circumstances they are rather "quiet" cells. All of that changes when an injury occurs; those Schwann cells de-differentiate back to a stem-cell-like state and play an important role in bridging the gap to repair damaged neurons."
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