Bone Marrow Stromal cells(BMSCs) are mesenchymal elements that normally provide structural and functional support for hematopoiesis.The cytokines and growth factors excreted by BMSCs consist the microenvironment which plays a crucial role in haemopoietic stem cells differentiation and development.Studies show that the cytokines and growth factors that regulate haemopoietic stem cells could also regulate central and peripheral nervous system.Our former research have confirmed that BMSCs can directly regulate the differentiation of Neural stem cells (NSCs) into high proportional neurons,furthermore the dissolvable molecules excreted by BMSCs play a key role during this process,surpported by the study of Bone Marrow Stromal cells conditioned medium(BMSCs-CM).The ingredient of BMSCs-CM plus 2%B27 supplement is too complicated to be analyzed.