Stromal cell derived factor-1 inducing targeted migration of neural stem cells

Abstract

Objective To investigate the effect ofstromal cell derived factor-1 (SDF-1) on the regulation of neural stem cells (NSCs) migration.Methods NSCs were obtained from the cerebral cortex of embryonic rats and cultured in serum-free medium,and their stem cell properties were assessed by means of induced differentiation in vitro into neurons and astrocytes.After in vitro cell culture,the purity of NSCs and the co-expression rate of CXCR4/nestin were detected by flow cytometry.Blind-well chambers were employed to detect the chemotactic effects of SDF-1 by counting the cells which had crossed a 8 μm pore membrane when confronted with varying concentrations of SDF-1 (0,1,10,50,100,500 and 1000 ng/mL),and the distribution of cells migrated out of the same neurosphere was overviewed by μ-slides in the persistent concentration gradient of SDF-1.Results Neurospheres were formed by persistent proliferation of NSCs, which were capable of differentiating into neurons (β-tubulin+) and astrocytes (GFAP+) in media without mitogens,and flow cytometry analyses showed that most of the cultured cells expressed nestin and the co-expression rate of CXCR4/nestin was nearly 80%.SDF-1 showed great chemotaxis to NSCs,and the amount of cells having migrated through the membrane in 500 ng/ml SDF-1 group was higher than that in other groups (P<0.05).When the cells were confronted with a linear concentration gradient (from 500 to 0 ng/mL),which was generated by diffusion and stable for at least 48 h,the cells migrated out ofa neruosphere could distribute irregularly with more cells locating in the region of higher concentration of SDF-1 and longer migration distance away from the center of the neurosphere than the opposite.Conclusion SDF-1 binding to its specific receptor CXCR4 was capable of inducing NSCs migrating directionally to the source of SDF-1. Key words: Neural stem cells; Stromal cell derived factor-1; Migration; Blind-well chamber