Abstract: A preparation of silver nanoparticles has been found to be effective in improving functional and behavioral recovery from traumatic spinal cord injury. The silver nanoparticles are provided in a non-flowable gel vehicle, from which they are release at high efficiency, that is applied locally at the site of the spinal cord injury. Silver nanoparticle formulations described herein were found to modify the M1/M2 macrophage phenotype ratio and provides a synergistic effect in the combination with arginase to promote healing processes at the treated injury site, reducing postinjury inflammation.