Gliomas induce astrogliosis and scar-formation. a. Aldh1l1-eGFP-Scid control mice show low or no GFAP expression in the cortical gray matter. b,c. Aldh1l1-eGFP-Scid mice injected with GBM22 glioma cells showed widespread astrogliosis around the tumor mass and upregulate the astrogliosis marker GFAP. Collapsed stacks of confocal images of 50 μm slices from PFA-perfused brain tissue. d. Confocal image of a 300 μm acute GBM22-bearing Aldh1l1-eGFP brain slice that was fixed in PFA following electrophysiological recordings shows an increase in GFP intensity surrounding the glioma (a,b,c,d n = 6). e,f. Similar observations (GFAP upregulation, also see i. and enhanced GFP signal in astrocytes adjacent to the tumor) were made when D54-GFP glioma cells were injected (e,f n = 4). g. Western blotting for GFAP in control and peritumoral cortex. h. GFAP protein levels were quantified as fold change in protein expression with GAPDH used as a loading control (g,h n = 6). i. High magnification images of GFAP labeling in a slice from a D54-tumor bearing animal indicated elongation of astrocytic processes and scar-formation along the tumor border (n = 4). j. Hematoxylin & Eosin staining of Shams, GBM22 and D54 tumor-bearing mice (n = 3 in each group).