Transplantation of neural precursor cells (NPCs) has promise as a cell-replacement therapy in neurodegenerative disorders; however, their efficacy is hampered by poor migration into, and population of, the host tissue. Here, the authors found that differentiating NPCs formed spherical clusters and secreted vascular endothelial growth factor and fibroblast growth factor 2, and that the secretion of these factors prevented the migration of the NPCs' neuronal progeny. Inhibition of these auto-attractive mechanisms enhanced the migration of grafted differentiating NPCs into rodent CNS tissue. Therefore, therapy based on these mechanisms might increase the effectiveness of neural transplants.