Corticospinal Tract Axons Regenerate after Spinal Cord Injury: Growth from the Injured Tip of Axon
Neural stem cells or neural progenitor cells have been extensively studied in spinal cord injury (SCI) rat models to attempt to reconnect injured circuits to restore function. Attempts have shown significant success, and further studies have revealed corticospinal tract (CST) axon growth into the neural stem cell graft. The purpose of this study is to understand whether CST axons undergo regeneration, regenerative sprouting, or sprouting into a neural stem cell graft. The animals were grafted with E14 spinal neural progenitor cells in a C4 dorsal column lesion for this study. The rat models were then injected with a small volume and low concentration of a tracer, AAV8-CAG-rCOMET or biotinylated dextran amine, in the motor cortex of the brain to label a few individual axons in order to visualize their growth pathway. Through the visualization on the confocal microscope, the injured axons of the CST are shown to regenerate into the graft cells. There was minimal regenerative sprouting and no sprouting seen with this model. Thus, CST axons regenerate into a neural stem cell graft.