Single Cell Sequencing of Image Guided Biopsies Identifies Spatial and Temporal Heterogeneity in High Grade Glioma. (16th November 2020)

• Record Type: Journal Article
• Authors: Patel, Kunal S; Kawaguchi, Riki; Everson, Richard G; Liau, Linda M; Ellingson, Benjamin; Kornblum, Harley I
• Is Part Of: Neurosurgery. Volume 67(2010)Supplement 1
• Publication Date: 2020-11-16
• Subjects: Nervous system -- Surgery -- Periodicals; 617.48005
• DOI: 10.1093/neuros/nyaa447_831
• Languages: English
• ISSNs: 0148-396X

Abstract

Abstract: INTRODUCTION: Both therapy and molecular investigations involving glioma focus on the contrast enhancing (CE) portion of the tumor. However, given the invasive nature of glioma, residual tumor cells responsible for recurrence likely exist in the non-enhancing (NE) region. METHODS: In 3 patients undergoing surgery for malignant glioma, we used pre-operative magnetic resonance images to prospectively identify biopsy targets in the CE region and locations 0.5-2.0 cm beyond the CE edge. A total of 9 image guided biopsy specimens underwent single cell sequencing to generate 12, 528 single cell RNA profiles. RESULTS: Tumor cells clustered into three predominant groups: tumor cells with astrocyte markers (ASC-like), tumor cells with oligodendrocyte markers (ODC-like), and tumor cells with neither marker. This last group consisted of a small proportion of tumors cells and expressed neural stem cell markers (PROM1, NES). Pseudotime analysis, which temporally orders single cells based on gene expression, consistently positioned this group as branching off into either ASC-like or ODC-like cells. CE regions had different cellular compositions than NE regions, with higher proportions of tumor, endothelial and CD8+ t-cells. There were significant differences in gene expression between CE and NE tumor cells, with increased inflammation and hypoxia in the CE region versus increased proliferative markers in the NE region. There were smaller differences in non-tumor cells between these regions, but in the NE region, non-tumor oligodendrocytes expressed pro-apoptotic factors and immune cells expressed anti-inflammatory factors. Using location and cell density data, we modeled expected tumor burden, predicting tumor cells up to 1.5 cm beyond the CE region of the tumor. CONCLUSION: Single cell sequencing illustrates heterogenous glioma cell types and suggests a temporal relationship between tumor cell types. CE and NE regions exhibit different tumor and non-tumor cell populations as well as different gene expression profiles within individual cell types. There remains a significant tumor cell burden in the NE portion of tumor, including actively proliferating cells and cells with stem cell markers existing in an anti-inflammatory microenvironment.