AN ORTHOTOPIC GL261–GCAMP6S MOUSE MODEL TO STUDY GLIOBLASTOMA GROWTH AND TUMOUR‑RELATED EPILEPSY

Introduction: Glioblastoma (GBM) is the most common malignant primary brain tumour in adults, characterised by rapid local growth, pronounced cellular and molecular heterogeneity, resistance to current therapies, and a strong propensity for recurrence. Clinically, GBM is frequently associated with tumour-related epileptic activity, but mechanistic links between tumour progression, microenvironmental remodelling, and network hyperexcitability remain poorly understood.
Aims: To address this gap, we established an orthotopic GBM model by implanting verified viable mKate2-labelled GL261 cell spheroids into the cortex of adult GCaMP6s-expressing mice. Chronic in vivo two-photon imaging longitudinally tracked spheroid growth and invasion dynamics. At defined time points, brains were collected for immunohistological analysis to quantify tumour size and characterise microenvironmental changes.
Results: Chronic two-photon imaging revealed progressive expansion of the GL261 spheroid and its integration into surrounding cortical tissue in GCaMP6s mice. Immunohistological snapshots at different disease stages confirmed increasing tumour volume and dynamic remodelling of the tumour microenvironment.
Conclusion: The orthotopic GL261–GCaMP6s mouse model integrates structural, cellular, and functional readouts of GBM progression. Future chronic recordings from flexible organic surface electrodes will enable high-resolution correlation of local field potential and seizure activity with tumour growth and microenvironmental changes. This approach will facilitate the identification of markers driving tumour-related epilepsy and support targeted therapies for GBM and associated seizures.