Cellular composition and molecular signatures of the
glioma core compared with infiltrative margins are different, and it is well known that the
tumor edge is enriched in microglia. In this review of the literature, we summarize the role of the peritumoral area in high-grade
gliomas (HGGs) from surgical and
biological points of view. There is evidence on the dual role of microglia in HGGs-a scavenger-tumoricidal role when microglia are activated in an M1 phenotype and a role favoring
tumor growth and infiltration/migration when microglia are activated in an M2 phenotype. Microglia polarization is mediated by complex pathways involving cross-talk with
glioma cells. In this scenario, extracellular vesicles and their
miRNA cargo seem to play a central role. The switch to a specific phenotype correlates with prognosis and the pathological assessment of a specific microglial setting can predict a patient's outcome. Some authors have designed an engineered microglial cell as a biologically active vehicle for the delivery of intraoperative near-infrared
fluorescent dye with the aim of helping surgeons detect peritumoral infiltrated areas during resection. Furthermore, the pharmacological modulation of microglia-
glioma cross-talk paves the way to more effective
therapies.