Role of chemotactic factors in glioma stem cells inducing the migration of neural stem cells in vitro

Abstract

Objective To observe the migration of neural stem cells (NSCs) to glioma stem cells (GSC), and to investigate the chemotactic mechanism. Methods GSCs were cultured and expanded in stem cell medium from human glioma cell line U251 and surgically resected specimens of human gliomas. All the GSCs were identified by using flow cytometry and Western blotting. Migrations of NSCs to GSCs,differentiated cells and concentration gradient fluid of growth factors were detected by Transwell assay. Concentrations of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) secreted by GSCs and differentiated cells were determined by using enzyme linked immunosorbent assay (ELISA). The in vitro migration of NSCs (marked by Dio) to GSCs (marked by Dil) was observed by using fluorescent microscopy. Results Neurospheres of GSCs, with high expression of stemness markers (CD133: 11.02％-33.55％ ), were cultured in stem cell medium and could be differentiated in serumcontaining medium. After differentiation, the expression of stemness markers was decreased, while the marker of glial fibrillary acidic protein (GFAP) was increased ( P ＜ 0.05). Meanwhile, the concentrations of VEGF and bFGF secreted by GSCs were higher than those by differentiated cells. Both GSCs and differentiated cells could induce the migration of NSCs, while GSCs showed significantly stronger chemotactic effect (P ＜ 0. 05). The migratory ability of NSCs might be positively correlated with the concentration of growth factors in chemotactic fluid ( P ＜ 0. 05 ). NSCs could migrate to GSCs and surround the neurosphere of GSCs, which displays cytostatic effect in vitro. Conclusion Gliona stem cells could induce the migration of NSCs and show enhanced chemotaxis compared with the differentiated cells. This chemotactic mechanism might be related to high concentrations of growth factors secreted by GSCs. Migration of NSCs to GSCs displays cytostatic effect in vitro. Key words: Neural stem cells; Glioma stem cells; Migration; Chemotactic factors