Role of the Tumor Microenvironment in Aggressive Meningiomas

The objective of this study is to characterize the different cellular populations of the microenvironment of meningioma, particularly the immune and vascular cell populations, in order to better understand their role in the initiation and progression of this tumor. For this purpose, we will use MRI imaging and surgical biopsies of the dura mater and meningioma to characterize cellular phenotypes and their interactions in the tissue microenvironment. The research will be conducted on a cohort of patients treated for meningioma in neurosurgery services. Samples required for the study will be obtained from surgical waste of patients who underwent meningioma resection. Data necessary for the study will be collected from the patient's medical records, MRI examinations, and data specific to the characteristics of the surgical waste. Prospective patients will be informed of the study through an information note. Patients who do not object to their participation will undergo neurosurgery intervention in accordance with the usual service protocol. During the intervention, surgical waste will be produced, including the meningioma and adjacent dura mater, which will be collected under the responsibility of the neuro-pathologist who will also take fragments for routine diagnostic histological analysis. We will then perform a targeted mutational analysis associated with neuropathological evaluation of the tumor grade in order to select 10 cases of grade I meningioma and 10 cases of grade II and III meningioma carrying the NF2 mutation. An in-depth analysis will then be carried out on these samples using 10x Genomic's single-cell RNA sequencing (scRNA-seq) technology. This analysis will help to understand the tumor's heterogeneity and establish the phenotype and differentiation trajectory of tumor cells, dura mater cells, and associated immune cells. In addition to RNA analysis, the expression of genetic signatures will be validated by RNAscope tests, while Hyperion imaging will allow visualization of the interrelationships between different types of cells and their spatial distribution. The iDISCO+ immunolabeling combined with three-dimensional fluorescence microscopy imaging will enable visualization of specific protein expression profiles of meningioma and dura mater cell types in 3D. Once the analyses are complete, meningioma and dura mater samples will be destroyed. Preoperative MRI images will also be retrieved and analyzed.