(A and B) Microarray data from DRG neurons. Expression vs. expression of young vs. aged DRGs in (A) naive conditions and (B) 4 days after nerve crush injury. Known markers of regeneration are highlighted in red. Lines in blue represent Fold Change = 2, blue numbers in each corner represent the number of genes over- or under-expressed by more than 2-Fold. (C to G) In vitro neurite outgrowth assays of DRG sensory neurons. Sensory neurons from naive young (C) or aged (D) DRGs from aged or young animals were purified and cultured for 17 hours and neurite outgrowth measured with Neuromath (E). Mean ± SEM, n = 3 independent experiments per group, NS = not significant with unpaired t-test. DRG sensory neurons from young (F) or aged (G) animals were purified 4 days after nerve injury, and cultured for 12 hours, revealing robust pre-conditioning responses.