Analysis of tumor microenvironment composition in vestibular schwannomas: insights into NF2-associated and sporadic variations and their clinical correlations.

Objective: Vestibular schwannomas (VS), benign tumors stemming from the eighth cranial nerve's Schwann cells, are associated with Merlin gene mutations, inflammation, and the tumor microenvironment (TME), influencing tumor initiation, maintenance, and potential neural dysfunction. Understanding TME composition holds promise for systemic therapeutic interventions, particularly for NF2-related schwannomatosis. Methodology: A retrospective analysis of paraffin-embedded tissue from 40 patients (2013-2020), evenly divided by neurofibromatosis type 2 status, with further stratification based on magnetic resonance imaging (MRI) progression and hearing function. Immunohistochemistry assessed TME components, including T-cell markers (CD4, CD8, CD25), NK cells (CD7), and macrophages (CD14, CD68, CD163, CCR2). Fiji software facilitated image analysis. Results: T-cell markers (CD4, CD8, CD7) exhibited low expression in VS, with no significant NF2-associated vs. sporadic distinctions. Macrophage-related markers (CD14, CD68, CD163, CCR2) showed significantly higher expression (CD14: p = 0.0187, CD68: p < 0.0001, CD163: p = 0.0006, CCR2: p < 0.0001). CCR2 and CD163 significantly differed between NF2-associated and sporadic VS. iNOS, an M1-macrophage marker, was downregulated. CD25, a regulatory T-cell marker, correlated significantly with tumor growth dynamics (p = 0.016). Discussion: Immune cells, notably monocytes and macrophages, crucially contribute to VS pathogenesis in both NF2-associated and sporadic cases. Significant differences in CCR2 and CD163 expression suggest distinct immune responses. Regulatory T-cells may serve as growth dynamic markers. These findings highlight immune cells as potential biomarkers and therapeutic targets for managing VS.

Development of a vestibular schwannoma tumor slice model for pharmacological testing.

BACKGROUND: Our goal was to develop a 3D tumor slice model, replicating the individual tumor microenvironment and for individual pharmaceutical testing in vestibular schwannomas with and without relation to NF2. METHODS: Tissue samples from 16 VS patients (14 sporadic, 2 NF2-related) were prospectively analyzed. Slices of 350 µm thickness were cultured in vitro, and the 3D tumor slice model underwent thorough evaluation for culturing time, microenvironment characteristics, morphology, apoptosis, and proliferation rates. Common drugs - Lapatinib (10 µM), Nilotinib (20 µM), and Bevacizumab (10 µg/ml) - known for their responses in VS were used for treatment. Treatment responses were assessed using CC3 as an apoptosis marker and Ki67 as a proliferation marker. Standard 2D cell culture models of the same tumors served as controls. RESULTS: The 3D tumor slice model accurately mimicked VS ex vivo, maintaining stability for three months. Cell count within the model was approximately tenfold higher than in standard cell culture, and the tumor microenvironment remained stable for 46 days. Pharmacological testing was feasible for up to three weeks, revealing interindividual differences in treatment response to Lapatinib and intraindividual variability in response to Lapatinib and Nilotinib. The observed effects were less pronounced in tumor slices than in standard cell culture, indicating the model's proximity to in vivo tumor biology and enhanced realism. Bevacizumab had limited impact in both models. CONCLUSION: This study introduces a 3D tumor slice model for sporadic and NF2-related VS, demonstrating stability for up to 3 months, replication of the schwannoma microenvironment, and utility for individualized pharmacological testing.