Mesenchymal Stromal-Like Cells in the Glioma Microenvironment: What Are These Cells?

SIMPLE SUMMARY: We review here what is currently known about the role of mesenchymal stromal-like cells, which complicate our understanding of the glioma microenvironment. We provide an overview of the major studies on these cells, highlighting their role in tumor progression and prognosis. Researchers and clinicians should consider these cells to be an integral component of the glioma microenvironment, and of considerable potential value for future prognostic and therapeutic perspectives. ABSTRACT: The glioma microenvironment is a critical regulator of tumor progression. It contains different cellular components such as blood vessels, immune cells, and neuroglial cells. It also contains non-cellular components, such as the extracellular matrix, extracellular vesicles, and cytokines, and has certain physicochemical properties, such as low pH, hypoxia, elevated interstitial pressure, and impaired perfusion. This review focuses on a particular type of cells recently identified in the glioma microenvironment: glioma-associated stromal cells (GASCs). This is just one of a number of names given to these mesenchymal stromal-like cells, which have phenotypic and functional properties similar to those of mesenchymal stem cells and cancer-associated fibroblasts. Their close proximity to blood vessels may provide a permissive environment, facilitating angiogenesis, invasion, and tumor growth. Additional studies are required to characterize these cells further and to analyze their role in tumor resistance and recurrence.