Fig. 4: A function blocking antibody directed towards integrin α3β1 reduces blood vessel density in GBM tumors in organotypic culture.

a Schematic diagram of the experimental procedure. Briefly, GBM tumors (ccf4259, ccf4268, ccf4272, and DI247) cut into ~4 mm in diameter were cultured in Matrigel in neurobasal medium supplemented with 1 ng/ml EGF and 1 ng/ml bFGF. On day 2, anti-integrin α3 subunit blocking antibody or control mouse IgG was injected at three places per tumor piece to achieve ~5 µg/ml in tumor volume. The same injection was repeated on day 6. On day 9, tumors were fixed in 10% formalin and paraffin-embedded. Sections were labeled with rabbit anti-CD31 antibody and Alexa-Fluor-488 goat anti-rabbit IgG, followed by DAPI nuclear stain and imaging. b Representative immunofluorescent images from organotypic culture of tumor ccf4272 are shown. c Percent CD31-positive area per field was obtained by image processing using ImageJ. n denotes the number of different fields, for ccf4269, n = 44 for mouse IgG and n = 95 for anti-integrin α3; for ccf4268, n = 39 for mouse IgG and n = 103 for anti-integrin α3; for ccf4272, n = 57 for mouse IgG and n = 82 for anti-integrin α3; for DI-247, n = 59 for mouse IgG and n = 88 for anti-integrin α3. The boxes indicate the first and third quartiles, bands indicate medians, and the whiskers indicate ±1.5 interquartile range. A linear mixed model was used for statistical analysis (p < 0.001). Source data are provided as a source data file.