Effective Repair of Traumatically Injured Spinal Cord by Nanoscale Block Copolymer Micelles

Spinal cord injury (SCI) results in immediate disruption of neuronal membranes followed by extensive secondary neurodegenerative processes. A key approach for repair of SCI is sealing the damaged membranes early. Here we show that axonal membranes injured by compression can be effectively repaired by using self-assembled monomethoxy poly(ethylene glycol)-poly(D,L-lactic acid) di-block copolymer micelles (60 nm diameter). Injured spinal tissue incubated with micelles showed rapid restoration of compound action potential and reduced calcium influx into axons. Much lower micelle concentration is required for treatment than the positive control, polyethylene glycol. Intravenously injected micelles effectively recovered the locomotor function and reduced the volume and inflammatory response of the lesion in SCI rats. The micelles showed no adverse effects after systemic administration to live rats. Our results suggest that copolymer micelles can interrupt the spread of primary SCI damage with minimal toxicity.