Spinal cord injuries often lead to permanent paralysis and loss of sensation because the damaged nerve fibers can't regenerate, Northwestern University scientists said. Although nerve fibers or axons have the capacity to re-grow, they don't because they're blocked by scar tissue that develops around the injury.

The nanogel developed at the university's Feinberg School of Medicine inhibits formation of scar tissue and enables the severed spinal cord fibers to regenerate and grow, the scientists said.

The gel is injected as a liquid into the spinal cord and self-assembles into a scaffold that supports new nerve fibers. When the gel was injected into mice with a spinal cord injury, after six weeks the animals had a greatly enhanced ability to use their hind legs and walk.

"It's important to understand that something that works in mice will not necessarily work in human beings," said study leader Dr. John Kessler, who noted that if the gel is eventually approved for humans, a clinical trial could begin within several years.

The research is reported in the Journal of Neuroscience.