Os10.6.a glioblastoma cells imitate neuron’s excitability in acute and organotypic human brain slices

Abstract BACKGROUND Glioblastoma (GBM) is a highly lethal cancer with a low treatment success rate due to its inter- and intra-patient molecular and physiological heterogeneity, and its complex interaction with brain tissue. Neuron-to-brain tumor-synaptic-communications (NBTSCs) are believed to contribute to glioma progression and tumor-induced epilepsy. However, the physiology of these synaptic interactions in the tumor-infiltrated human neocortex remains largely uncharacterized. In this study, we investigated the intrinsic electrical properties of cells and NBTSCs in the tumor-infiltrated human cortex. MATERIAL AND METHODS We established a unique experimental workflow that enables us to investigate glioma cells in acute and cultured human tumor-infiltrated brain slices. We utilized an adeno-associated virus-assisted gene delivery technique to selectively express fluorescence proteins in a cell-type specific manner. By performing fluorescence-guided whole-cell patch clamp recording, we characterized the electrophysiological properties of glioma cells and neurons under the tumor microenvironment. RESULTS We observed that glioma cells from tumor-infiltrated human brain samples display relatively depolarized -32.59 + 3.16 mV resting membrane potential and high input resistance of 1.73 + 0.43 GΩ, with 44.44% of glioma cells exhibit spikelets or distorted-action potentials upon current injection. Consistent with previous studies, some glioma cells (11.8%) from both acute and cultured human brain slices exhibit spontaneous excitatory postsynaptic currents (sEPSC). In addition, the tumor-infiltrated microenvironment significantly influences the proximal neurons’ physiology and the neuronal microcircuitry. Neurons within the tumor region show abnormal intrinsic electrical properties, depolarized resting membrane potential (-37.66 + 4.32 mV), and a significant reduction in spontaneous synaptic input frequency. CONCLUSION Collectively, we consolidate the existence of NBTSCs in human cancer patients and unprecedentedly reveal that glioma cells exhibit neuron-like excitability, which is contrary to the common understanding that they are considered as non-excitable. Under the tumor microenvironment, neurons display hyperexcitability. Our newly established organotypic human brain slice culture platform provides potential grounds for exploring further the biological characteristics of gliomas. SUPPORT/DISCLOSURE This study is supported by grants to AK (DCCC Consortium grant number R295-A16770 funded by the Danish Comprehensive Cancer Center); to MC (Lundbeck-NIH grant number R325-2019 funded by the Lundbeck Foundation, DFF-1 project 37741 funded by the Independent Research Fund Denmark).