For decades, numerous investigations have only focused on axon regeneration to restore function after traumatic spinal cord injury (SCI), as interrupted neuronal pathways have to be reconnected for sensorimotor and autonomic recovery to occur.
This is a schematic illustration of neuronal relays in the restoration of complete spinal cord injury.
Credit: Neural Regeneration Research
Experimental approaches have ranged from drug delivery and cell transplantation to genetic manipulations.
Certainly, it would be an extraordinary achievement for injured axons to regenerate over long distances, to form synapses with target neurons, and to result in dramatic functional improvement.
Dr. Shaoping Hou from Drexel University in USA considered that these efforts have been rewarded with limited success to date suggesting that axon regeneration alone may be insufficient to repair compromised functions. Upon exogenous stimulation, corticospinal tract (CST) axons do not, or are less responsive. However, even terminals of the longest regenerated sensory axons are usually far from the original target.
To reestablish neuronal pathways, introduction of a new host or graft-derived neuron may therefore be necessary to relay supraspinal signal transmission to target neurons.
The relevant study has been published in Neural Regeneration Research (Vol. 9, No. 12, 2014).
Hou S. "Relay strategies combined with axon regeneration: a promising approach to restore spinal cord injury." by Shaoping Hou (Spinal Cord Research Center, Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA), Neural Regen Res. 2014;9(12):1177-1179.