Regeneration of dorsal column fibers into and beyond the lesion site following adult spinal cord injury

Regeneration is abortive following adult mammalian CNS injury. We have inve stigated whether increasing the intrinsic growth state of primary sensory n eurons by a conditioning peripheral nerve lesion increases regrowth of thei r central axons. After dorsal column lesions, ail fibers stop at the injury site. Animals with a peripheral axotomy concomitant with the central lesio n show axonal growth into the lesion but not into the spinal cord above the lesion. A preconditioning lesion 1 or 2 weeks prior to the dorsal column i njury results in growth into the spinal cord above the lesion. In vitro, th e growth capacity of DRG neurite is also increased following preconditionin g lesions. The intrinsic growth state of injured neurons is, therefore, a k ey determinant for central regeneration.