Figure 1. Multicellular glioma cell networks and perivascular invasion in mouse brain.

Morphological pattern and quantitative cell-cell junction analysis of interstitial networks (a-d) and perivascular invasion (e-h) in human glioblastoma xenografts. E-98 and E-468 cell lines were implanted into mouse brain and after 28 days peritumor regions were assessed by confocal microscopy (in 200 μm-thick brain slices). Identification of glioma cells by human nestin/vimentin staining. Brain stroma was detected by GFAP (astrocytes) and blood vessels by laminin or CD31 staining. Arrowheads indicate filamentous (a) or linear (e) contacts between glioma cells. Numbers in (a) indicate glioma cell bodies connected with filamentous cell protrusions. Tu, tumor. Example images in (a, e) represent tumors from 3 mice per PDX line. Data represent 63–79 (b), 42 (c, d), 36–48 (f) and 18–33 cells (g, h) from 2 representative mice from three independent implantation series. Scatter dot plots show the medians (red line) and values representing individual cells (b, c, f, g); in (d, h) values display relative fractions of connected glioma cells interacting with 0 up to ≥10 connected cells (boxes), median (red square), 25/75 percentiles (whiskers). Relative fractions of glioma cells connected with linear (E-98) or filamentous (E-468) junctions (h). Scale bars, 50 μm.