Figure 1.

The three types of glioblastoma stem cell microenvironments: (A) the perivascular niche, where GSCs lie in close contact with the endothelium, a favorable ambient that promotes tumor resilience and proliferation; (B) the necrotic niche, at the tumor core, where hypoxia and lack of nutrients drive the formation of new vessels by diverse processes. Under these undesirable conditions, cells develop adaptive anaerobic metabolism and quiescence; (C) the invasive front, at the tumor margin, where GSCs exhibit an infiltrative nature and make use of preexisting healthy vessels to spread throughout the healthy parenchyma. GSC, glioblastoma stem cell; TAM, tumor-associated macrophage.