Neural stem cell migration toward gliomas in vitro

Various in vivo studies demonstrated a migration tendency of neural stem cells (NSCs) toward gliomas, making these cells a potential carrier for delivery of therapeutic genes to disseminated glioma cells. We analyzed which factors determine NSC migration and invasion in vitro. Conditioned media prepared from 10 different human glioma cell lines, as well as 13 different tumor-associated growth factors, were analyzed for their chemotactic effects on murine C17.2 NSCs. The growth factor receptor status was analyzed by reverse transcriptase-polymerase chain reaction. Invasion of NSCs into multicellular tumor spheroids generated from 10 glioma cell lines was quantified. NSCs displayed a heterogeneous migration pattern toward glioma spheroids as well as toward glioma-cell-conditioned medium. Chemotactic migration was stimulated up to fivefold by conditioned medium as compared to controls. In coculture assays, NSC invasion varied from single cell invasion into glioma spheroids to complete dissemination of NSCs into glioma spheroids of different cell lines. Among 13 different growth factors, scatter factor/hepatocyte growth factor (SF/HGF) was the most powerful chemoattractant for NSCs, inducing a 2.5-fold migration stimulation. An antibody against SF/HGF inhibited migratory stimulation induced by conditioned media. NSC migration can be stimulated by various growth factors, similar to glioma cell migration. The extent to which NSCs infiltrate three-dimensional glioma cell aggregates appears to depend on additional factors, which are likely to include cell-to-cell contacts and interaction with extracellular matrix proteins.