Fig. 3: PCs are enriched in ETMR hypercellular regions, which correlate with stem-like cell fates.

A, B Muliplex IF analysis of a human ETMR FFPE section (n = 1). A Representative multiplex IF images showing merged channels for smooth-muscle cells (ACTA2+), PC (PDGFRb+), EC (CD31+) and DAPI nulear staining. Insets present individual channels of selected areas (dashed boxes 1 and 2), revealing the close juxtaposition of PC to EC in vessel walls (box 2). B Amplified image of the region within box 1 (panel A), depicting RG-like cells (NEShigh/SOX2+), NProg-like cells (SOX2+/NESlow−), Nb-like cells (MAP2+) and PC (PDGFRb+). The main panel shows merged channels, while insets display selected single channels (scale bar, 10 μm). C Quantitative analysis of tumor subpopulation proximities to PC regions described in (A). PC regions were defined by the areas enclosed by PDGFRb+ signal, as illustrated by the dashed line. Arrows indicate the shortest distances of individual cells to the nearest PC region. Distances were measured in pixels (px), and the distributions of each cell type and all segmented cells are shown in a histogram. NEShigh and SOX2 + /NESlow cells were significantly closer to PC regions than MAP2+ cells (n cells = 19,477; One-way Anova, F(3, 43917) = 1256, p value < 2e-16; post-hoc test TukeyHSD, p value < 0.00000001). D Quantitative IHC of human ETMR tumors. The left panel shows representative regions of interest (ROIs) of ETMR IHC sections as hypercellular (Hyper, pink) and hypocellular (Hypo, green) regions (also Suppl. Fig. S12). The right panel depicts DAPI+ cells (blue) and CD13 + PC (red) for further quantification (n samples = 4; field of view = 669 μm × 500 μm; n fields of view = 325). Scale bar = 100 μm. Boxplot shows median (center line), first and third quartile (bounds) and minima/maxima (whiskers) of all measurements of PC density in the Hyper vs Hypo regions. Data points 1.5× more than the interquartile range away from the box were considered outliers. One-sided Wilcoxon rank sum test with continuity correction. Sample type symbol created with BioRender.com. Data source of (D) is provided as a Source Data file.