Glioblastoma disrupts cortical network activity at multiple spatial and temporal scales

Abstract

The emergence of glioblastoma in cortical tissue is accompanied by signs of neural hyperexcitability that may manifest with symptoms ranging from mild cognitive impairment to convulsive seizures. Glioblastoma exploits the complex interplay between neurons and glia to create a microenvironment favorable for its own expansion, impeding efforts to achieve long-term clinical remission compared to other solid tumors. We employed a novel CRISPR-Cas9 in-utero electroporation system to induce two distinct GBM tumor models in immunocompetent mice in combination with prolonged EEG recording and single and 2-photon imaging of calcium and glutamate reporters to analyze dynamic changes in peritumoral cortical network activity at different spatial and temporal scales. We find a biphasic elevation in neuronal calcium activity followed by a linear but only partially overlapping accumulation of peritumoral glutamate during tumor growth indicating these processes are not entirely coordinated. The patterns are strongly influenced by tumor genetics. The global changes in excitability homeostasis alter the higher order modularity and connectivity patterns of local and remote neuronal populations and can transform inter-areal brain information processing over time.

Identification of functional immune and neuronal tumour cells in glioma

“…2-photon in vivo imaging 2-photon images of calcium reporter activity were assessed according to previously published protocols 61 . Briefly, calcium reporter activity was acquired using a Prairie Ultima IV 2-photon microscope through a 25× objective, 1.1 NA, or a 16× objective, 0.8 NA, at 920 nm (GCaMP) under spiral (10-20 Hz frame rate) or resonant scan mode (30)(31)(32)(33)(34)(35).…”

“…This FUCCI construct allows for identification of cell nuclei that are transitioning from S to G2/M phases. Mouse surgeries were performed according to our previously published protocols 61 .…”