Transneuronal Delivery of Cytokines to Stimulate Mammalian Spinal Cord Regeneration

The spinal cord contains multiple fiber tracts necessary for locomotion. However, as a part of the central nervous system, they are extremely limited in regenerating after injury. Many of these key fiber tracts originate from deep brain stem nuclei that are difficult to access. Here we detail a new methodology that achieves functional regeneration in mice after a complete spinal cord crush, describing the crushing procedure itself, intracortical treatment application, and a set of appropriate validation steps. The regeneration is achieved by the one-time transduction of neurons in the motor cortex with a viral vector expressing the designer cytokine hIL-6. This potent stimulator of the JAK/STAT3 pathway and regeneration is transported in axons and then transneuronally delivered to critical deep brain stem nuclei via collateral axon terminals, resulting in previously paralyzed mice walking again after 3-6 weeks. With no previously known strategy accomplishing this degree of recovery, this model is well suited to studying the functional impact of compounds/treatments currently only known to promote anatomical regeneration.