NGF and peripheral nerve lesion: During the repair phase following peripheral nerve lesion, dedifferentiated Schwann cells secrete a variety of neurotrophic factors and cytokines including NGF, BDNF, NT-4/5, FGF-2, IGF-1, IL-6, and IL-1ß that support neuronal survival and regenerative growth of axons (Chen et al., 2007; Navarro et al., 2007).