KLS Martin Award - Spatial Transcriptomics Analysis Uncovers Cellular Interactions Between Glioblastoma and Neurons in a Novel Ex Vivo Human Brain Slices

Introduction: Glioblastomas(GBM) are highly aggressive tumors with a 5-year survival rate of < 5%. While the invasive and proliferative mechanisms of GBM have been extensively studied, the effects of tumor spread on the surrounding brain parenchyma are still poorly understood. In this study, we utilize a novel long-term human brain slice model combined with patient-derived GBM organoids(GBOs) to investigate the complex interactions between GBM and brain parenchyma.

Methods: GBO were established from tumor tissue obtained from 30 patients who underwent GBM surgical resection. Brain specimens were obtained from patients undergoing epileptogenic disconnection surgery and were acutely oxygenated in artificial CSF, cultured in neuroprotective media, and transduced with GFP-fluorescent. Co-cultures of GBOs with brain slices were established, followed by spatial transcriptomics to compare the GBO core, brain slice edge, and FACS-sorted brain-tumor interface, distinguishing invasive GBO from invaded parenchymal cells.

Results: Upon establishing the co-cultures, live imaging was employed to track cellular invasion and examine cell-to-cell interactions between GBO cells and brain cells. This revealed direct interactions between invading GBO cells and brain cells, with increased apoptosis observed in neurons closer to the invading tumor compared to those at a distance. Gene ontology analysis highlighted an increase in neuronal activity and postsynaptic excitation in invaded brain parenchyma relative to outer brain tissue. At the molecular level, there was a marked rise in glutamate secretion at the brain-tumor interface following GBO implantation, along with a 1.8-fold upregulation of SLC7A11 (P < 0.001). Invasive GBO cells avoided auto-excitotoxicity by downregulating NMDA and AMPA receptors compared to normal brain parenchyma (P < 0.001). Finally, application of the AMPA receptor inhibitor CNQX significantly reduced neuronal apoptosis near the invasion front (P < 0.001).

Conclusion : Our brain slice-GBO model demonstrates the critical role of ionotropic glutamate receptor modulation in tumor invasion, highlighting potential therapeutic targets for intervention.