The response of dorsal root ganglion axons to nerve growth factor gradients depends on spinal level.

Directed sensory axon regeneration has the potential to promote functional recovery after peripheral nerve injury. Using a novel guidance assay to generate precisely controllable nerve growth factor gradients, we show for the first time that the guidance and outgrowth response of rat dorsal root ganglion neurons to identical nerve growth factor gradients depends on the rostrocaudal origin of the dorsal root ganglion explant. These findings have implications for the study of peripheral nerve regeneration in response to exogenous neurotrophins such as nerve growth factor, and provide new insight into the clinical potential of nerve growth factor in the treatment of nerve injury.