Recapitulation of cancer stem cell niches in glioblastoma on 3D microfluidic cell culture devices under gravity-driven perfusion

The low survival rate of patients with glioblastoma is in part due to the heterogeneity in the cell population of glioblastoma that includes cancer stem cells (CSCs). CSC niches include a hypoxic core that is also closely linked to self-renewal ability, migration, and drug resistance. Here, we report a CSC culture method in three-dimensional microfluidic cell culture devices under gravity-driven perfusion, which we dub hypoxia chips (H-chips). In H-chips, glioblastoma cells, U87, spontaneously formed spheroids within 12 h, even without any addition of growth factors. Compared to monolayer-cultured cells in dishes, spheroids in H-chips showed higher expression of CSC markers, such as hypoxia-inducible factor-1α (HIF-1α), CD133, and nestin. Spheroids in H-chips were more resistant to doxorubicin than monolayer-cultured ones in dishes. Transcriptional profiling revealed that the expression of interleukin-6 (IL-6), one of the inflammatory cytokines, was higher in spheroids in H-chips than in monolayer-cultured cells in dishes. IL-6 depleted cells failed to form spheroids in H-chips, and their drug resistance decreased. These results suggest that in H-chips, glioblastoma cells increased the production of IL-6, and promoted spheroid formation and other cancer stem cell properties, such as drug resistance. Our microfluidic cell culture method is highly useful for recapitulating CSC niches.