Neural Stem Cell Transplantation and CNS Diseases

In neurological disorders, pathological lesions in the central nervous system (CNS) may be globally dispersed throughout the brain or localized to specific regions. Although native neural stem cells (NSCs) are present in the adult mammalian brain, intrinsic self-repair of injured adult CNS tissue is inadequate or ineffective. The brain's poor regenerative ability may be due to the fact that NSCs are restricted to discrete locations, are few in number, or are surrounded by a microenvironment that does not support neuronal differentiation. Therapeutic potential of NSC transplantation in CNS diseases characterized by global degeneration requires that gene products and/or replaced cells be widely distributed. Global degenerative CNS diseases include inherited pediatric neurodegenerative diseases (inborn errors of metabolism, including lysosomal storage disorders (LSDs), such as Tay-Sachs-related Sandhoff disease), hypoxic or ischemic encephalopathy, and some adult CNS diseases (such as multiple sclerosis). Both mouse and human NSCs express many chemokines and chemokine receptors (including CXCR4 and adhesion molecules, such as integrins, selectins, and immunoglobulins) that mediate homing to sources of inflammatory chemokines, such as SDF-1α. In mammalian brains of all ages, NSCs may be attracted even at a great distance to regions of neurodegeneration. Consequently, NSC transplantation presents a promising strategy for treating many CNS diseases.