Additional Supporting Information may be found in the online version of this article.

sc-12-1092_sm_SupplFigure1.tif1347KFigure S1. Differentiation capacity of TM and PT GICs. GICs formed neurospheres in culture. Neurosphere diameter after 7 days of culture was 160±32 μm in TM neurospheres and 73±15 μm in PT neurospheres (p<0.0001). Scale bar: 100 μm. Following neurosphere dissociation, individual cells, which stained positive for Sox2 (Scale bar: 10 μm), underwent astrocytic and neuronal differentiation in the presence of serum as determined by immunofluorescence with anti-GFAP and anti-Tuj1 antibodies respectively (Scale bar: 50 μm).
sc-12-1092_sm_SupplFigure2.tif1297KFigure S2. Patterns of cell invasion in neurosphere cultures. (A), (B), Neurospheres containing TM or PT cells were embedded in collagen matrices and the radial invasion of the matrix by tumour cells was visualized by light microscopy. Individual invasion, I, was determined by the mean distance from the edge of the neurosphere to the most distant migrating cells, whereas collective invasion, C, was quantitated by measuring the area between the edge of the neurosphere and the front of migrated cells. Histograms represent the mean±SD of three independent experiments. *p<0.005. (C), TM and PT cells migrating away from the neurospheres. Note the collective strands of invading PT cells (arrow). Scale bar: 10 μm.
sc-12-1092_sm_SupplFigure3.tif2542KFigure S3. In vivo association of PT cells to blood vessels. (A), Electron micrographs of semithin sections from the brain of mice xenografted with GICs. Arrows indicate tumour cells and asterisks indicate blood vessels. Scale bar: 3 μm. (B), Confocal microscopy of tissue sections showing colocalization of fluorescence signals from PT cells (CherryFP) and endothelial cells (Lectin). Scale bar: 10 μm. (C), (D), CFSElabeled tumor cells were cultured on a monolayer of HUVEC endothelial cells, and tumor cells from F1 (non-adherent and poorly-adherent cells) and F2 (strongly-adherent cells) fractions were counted by flow cytometry. *p<0.001. (E), Representative fluorescence image showing the morphology of TM and PT cells cocultured with HUVEC. Scale bar: 100 μm.
sc-12-1092_sm_SupplvideoS1.avi3407KVideo S1. Tracking of TM cells cultured on 1.5 kPa polyacrylamide matrix (Scale bar: 50 μm).
sc-12-1092_sm_SupplvideoS2.avi5216KVideo S2. Tracking of PT cells cultured on 1.5 kPa polyacrylamide matrix (Scale bar: 50 μm).

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