Researchers have discovered that nanospheres that are being used in drug delivery also have utility in repairing damaged nerve fibers in spinal cord injuries.

In animals with spinal cord injuries , polyethylene glycol, or PEG, has been found to specifically target damaged cells and seal the injured area, reducing further damage. It also helps restore cell function. Drug-delivery nanospheres, or synthetic "copolymer micelles" have also been found to have the same effect, with even better results.

Findings showed that cores made of particular materials work better than others at restoring function to damaged axons, which are slender extensions of nerve cells.

The research also showed that without the micelles treatment about 18 percent of axons recover in a segment of damaged spinal cord tested in a "double sucrose gap recording chamber." The micelles treatment boosted the axon recovery to about 60 percent. The researchers used the chamber to study how well micelles repaired damaged nerve cells by measuring the "compound action potential," or the ability of a spinal cord to transmit signals.

The experiment mimics what happens during a traumatic spinal cord injury. Findings showed that micelles might be used to repair axon membranes damaged by compression injuries, a common type of spine injury.

The researchers also tracked dyed micelles in rats, demonstrating that the nanoparticles were successfully delivered to injury sites. Findings also showed micelles-treated animals recovered the coordinated control of all four limbs, whereas animals treated with conventional polyethylene glycol did not.

Because of their nanoscale size, these micelles are not quickly filtered by the kidney or captured by the liver, enabling them to remain in the bloodstream long enough to circulate to damaged tissues. This study has been published in the recent issue of the journal Nature Nanotechnology.


Image: This image represents "copolymer micelles," tiny drug-delivery spheres that could be used in a new approach for repairing damaged nerve fibers in spinal cord injuries. The bottom graphs show data indicating damaged spinal cord tissue recovered its "action potential," or ability to transmit signals, after treatment with the micelles. (Purdue University's Weldon School of Biomedical Engineering)
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