Targeting axon guidance cues for neural circuit repair after spinal cord injury

At least two-thirds of spinal cord injury cases are anatomically incomplete, without complete spinal cord transection, although the initial injuries cause complete loss of sensory and motor functions. The malleability of neural circuits and networks allows varied extend of functional restoration in some individuals after successful rehabilitative training. However, in most cases, the efficiency and extent are both limited and uncertain, largely due to the many obstacles of repair. The restoration of function after anatomically incomplete injury is in part made possible by the growth of new axons or new axon branches through the spared spinal cord tissue and the new synaptic connections they make, either along the areas they grow through or in the areas they terminate. This review will discuss new progress on the understanding of the role of axon guidance molecules, particularly the Wnt family proteins, in spinal cord injury and how the knowledge and tools of axon guidance can be applied to increase the potential of recovery. These strategies, combined with others, such as neuroprotection and rehabilitation, may bring new promises. The recovery strategies for anatomically incomplete spinal cord injuries are relevant and may be applicable to traumatic brain injury and stroke.