Proposed Mechanistic Model for the Regeneration of Ascending Fibres in Pre-Conditioned DRG Neurons. Regenerative competence of pre-conditioned DRG neurons is described as a multi-faceted cascade of events: (1-2) SNI results in DRG and macrophage activation, upregulation of BDNF, cAMP and regeneration-associated genes (RAGs); all contributing to the beneficial phenotypic 'priming' of macrophage cells. (3) Facilitated entry of primed macrophage cells into the CNS compartment prior to CNS lesion. (4) SCI resulting in axonal injury, axon-myelin breakdown associated with the process of Wallerian degeneration. (5-6) Efficient removal of axonal and myelin debris by BDNF expressing macrophages beneficially activated with enhanced phagocytic capabilities, (7) consequently leading to axonal regeneration of the injured CNS-DRG branch. BNB = blood nerve barrier, RAGs = regeneration-associated genes, BBB = brain-blood barrier.