FGF2 and neurodegenerative disease: Neurotrophic factors or growth factors, such as EGF and FGF2, may stimulate the proliferation and differentiation of sub-ependymal neural stem cells into astroglia and ECs, restore the ependyma and maintain the microenvironmental homeostasis of the central nerve system, suggesting that the ependyma may be a valuable therapeutic target to prevent imbalanced-microenvironment-related neurodegenerative diseases.