The researchers observed groups of regenerating nerve fibers crossing the spinal cord injury site and the alignment of green cells forming myelin. Electron microscopic examination of the tissue showed that myelin was indeed produced around the axons by the transplanted cells.

"These results indicate that a number of factors including remyelination of axons may contribute to improvement in function following transplantation of OECs into the injured spinal cord," Sasaki says.

In other work, "tiny beads" (nanospheres) were found to release the enzyme that breaks down a component of the scar that forms after spinal cord injury. Dennis Stelzner, PhD, and his colleagues Donna Osterhout, PhD, and Julie Hasenwinkel, PhD, at SUNY Upstate Medical University and Syracuse University found that axonal growth, normally blocked by a component of the scar, is seen when the biodegradable nanospheres are injected.

Failure of axons to regenerate after spinal cord damage is attributed to a number of molecules present after injury that inhibit regrowth, including myelin (nerve covering) components and the scar tissue that forms after spinal cord injury, including the molecule chondroitin sulfate.

"We hypothesized that it would be possible to remove the inhibiting elements of chondroitin sulfate with the enzyme chondroitinase ABC (cABC) by delivering this enzyme in biodegradable nanospheres to the spinal injury, and thus enhance axonal regrowth and recovery of function," Stelzner says.

Stelzner and his colleagues created and injected nanospheres (3 m l of 10 mg/ml of cABC) directly into eight different tissue cultures containing chondroitin sulfate that blocked axonal growth, and axonal growth was seen within two days. The cABC continued to be released for at least two weeks, assessed
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Contact: Leah Ariniello
dawn@sfn.org
202-462-6688
Society for Neuroscience
26-Oct-2004