Abstract: We recently achieved significant functional recovery after a complete spinal cord injury, allowing previously paralyzed mice to walk again. This was accomplished by a single, unilateral application of an adeno-associated virus (AAV) carrying the cDNA for the designer cytokine hyper-interleukin-6 (hIL-6) into the sensorimotor cortex after spinal cord injury. This treatment resulted in the transneuronal delivery of the designer cytokine to neurons in  subcortical locomotor centers, axon regeneration of cortical- and serotonergic neurons across the lesion site, and functional recovery of hindlimb stepping. Here we briefly cover the historical context, current implications, and future perspectives surrounding this new achievement.