Mesenchymal Stem Cells and Fibroblasts Contribute to Microvascular Proliferation in Glioblastoma and are Correlated with Immunosuppression and Poor Outcome.

Microvascular proliferation (MVP) is a disease-defining hallmark of glioblastoma and other World Health Organization grade 4 gliomas. MVP also serves as a poor prognostic marker in various solid tumors. Despite its clinical significance, the mechanisms and biological consequences of MVP are controversial and remain unclear. In this study, we performed single-cell RNA sequencing on paired CD45-CD105+ vascular/perivascular stromal cells (PVSC) and CD45+CD105± immune cells from 16 primary glioma patient samples, both with and without MVP. This analysis revealed the presence of developmentally related mesenchymal stem cells alongside cancer-associated fibroblasts, pericytes, fibromyocytes, and smooth muscle cells within the CD45-CD105+ compartment. RNA velocity analysis identified PDGFRB as a putative driver gene guiding mesenchymal stem cells toward more mature PVSCs in the context of MVP. Signaling network analysis and digital spatial profiling uncovered interactions between PDGFRB+ PVSCs and immunosuppressive myeloid cell subsets enriched in the perivascular niche, suggesting targetable receptor-ligand interactions. Additionally, a gene signature of MVP-associated PVSCs from gliomas predicted worse prognosis in multiple other solid tumors. This study provides a transcriptomic cell atlas of PVSCs and immune cells in glioma, helping to refine the biological model of MVP which has traditionally focused on endothelial cells.