The approach was demonstrated in mice by the scientists in Ann Arbor, when the nanoparticles enhanced healing by reprogramming the aggressive immune cells.

"In this work, we demonstrate that instead of overcoming an immune response, we can co-opt the immune response to work for us to promote the therapeutic response," said Lonnie Shea, the Steven A. Goldstein Collegiate Professor of Biomedical Engineering.

Trauma of any kind kicks the body's immune response into gear. In a normal injury, immune cells infiltrate the damaged area and clear debris to initiate the regenerative process.

The central nervous system, which includes the brain and spinal cord, however, is normally walled off from the immune activity by the blood-brain barrier. But a spinal cord injury breaks that barrier, letting in overzealous immune cells that create too much inflammation for the delicate neural tissues. This leads to the rapid death of neurons, damage to the insulating sheaths around nerve fibers that allow them to send signals, and the formation of a scar that blocks the regeneration of the spinal cord's nerve cells.