Fig. 1: Study overview.

A GL261-GSCs were grown as neurospheres in stem cell medium. They were obtained from GL261 cells grown in adherence in differentiation medium. 5000 GL261-GSCs were intracranially injected into the right hemisphere of brains of syngeneic C57BL/6 mice in saline solution or 100 µM Tat-Cx43_266-283 (Tat-Cx43) or 250 µM temozolomide (TMZ). After 7 days, these treatments were intraperitoneally (IP) administered twice per week. Samples were collected from GBM-bearing mouse brains, including tumor core and surrounding tissue, at two stages of tumor growth, early (7 days post-implantation) and late (28 days post-implantation), and isolated nuclei for snRNA-Seq. snRNA-Seq was performed in all the in vitro and in vivo samples. Created with Bioicons: 96_well_plate and and microfluids_chip icons by Marcel Tisch licensed under CC0, Illumina_miseq icon and microtube-closed icons by DBCLS https://togotv.dbcls.jp/en/pics.html licensed under CC-BY 4.0. B Illustrative IBA1 immunofluorescence images of brains at 7 days post-implantation showing a small group of DAPI-stained tumor cells surrounded by IBA1⁺ TAMs at the injection site (dashed circle in upper panels), scale bar: 2 mm. Lower panels: zoomed-in images showing tumor cells intermingled and surrounded by IBA1⁺ TAMs (dashed line), scale bar: 50 µm. C Illustrative IBA1 immunofluorescence images of brains at 28 days post-implantation showing large tumors infiltrated and surrounded by IBA1⁺ TAMs, scale bar: 2 mm. Lower panels: zoomed-in images showing the border of the tumor together with a group of tumor cells infiltrating the brain parenchyma (dashed line), scale bar: 50 µm. Note the abundance of IBA1⁺ TAMs infiltrating and surrounding these tumors.