OBJECTIVE: To summarize the biological characteristics of neural stem cells, and the separation, purification, differentiation and source of neural stem cells.DATA SOURCES: An online search of Pubmed database was undertaken to identify English articles about the growth of neural stem cells in vitro published from January 2000 to October 2006 by using the keywords of neural stem ceils, bone marrow mesenchymal stem cells (BMSCs), umbilical cord blood stem cells, embryonic stem cells (ESC), separation methods, neural growth factor. And relevant articles published in IEEE/IEE Electronic Library (IEL) database, Springer Link database and Kluwer Online Joals were also searched.Chinese relevant articles published between January 2000 to October 2006 were searched with the same keywords in Chinese in Chinese joal full-text database.STUDY SELECTTON: The articles were primarily screened, and then the full-texts were searched. Inclusive criteria: ① Articles relevant to the biological characteristics and classification of neural stem cells; ② Articles about the source, separation and differentiation of the ESCs, BMSCs and umbilical cord blood stem cells. The repetitive studies and reviews were excluded.DATA EXTRACTION: Thirty articles were selected from 203 relevant articles according to the inclusive criteria.Articles were excluded because of repetition and reviews.DATA SYNTHESTS: Neural stem cells have the ability of self-renewing and high differentiation, and they are obtained from ESCs, nerve tissue, nerve system, BMSCs and umbilical cord blood stem cells. ESCs can be separated by means of mechanical dissociation is better than that of the trypsin digestion, BMSCs by density gradient centrifuge separation, hemolysis, whole-blood culture, etc., and umbilical cord blood stem cells by Ficoil density gradient centrifugation, hydroxyethyl starch (HES) centrifugation sedimentation, etc. Neural growth factor (NGF) and other factors play an important role in the growth of NSCs, such as transforming growth factor (TGF) is an important player in repairing organs, NGF accelerates the process of growth, insulin-like growth factor serves importantly in the differentiation of stem cells into neuron-like cells.CONCLUSTON: As unipotent stem cells, NSCs have the abilities of self-renewal and potential of high differentiation. The method of mechanical dissociation is better than trypsin digestion in e separating ESCs. However,density gradient centrifuge separation is better than other methods in the separation of the BMSCs. NGF and other factors play an important role in the growth of NSCs.