A Synthetic Polymer Scaffold Reveals the Self-Maintenance Strategies of Rat Glioma Stem Cells by Organization of the Advantageous Niche

Cancer stem cells (CSCs) are believed to be maintained within a microenvironmental niche. Here we used polymer microarrays for the rapid and efficient identification of glioma CSC (GSC) niche mimicries and identified a urethane-based synthetic polymer, upon which two groups of niche components, namely extracellular matrices (ECMs) and iron are revealed. In cultures, side population (SP) cells, defined as GSCs in the rat C6 glioma cell line, are more efficiently sustained in the presence of their differentiated progenies expressing higher levels of ECMs and transferrin, while in xenografts, ECMs are supplied by the vascular endothelial cells (VECs), including SP cell-derived ones with distinctively greater ability to retain xenobiotics than host VECs. Iron is stored in tumor infiltrating host macrophages (Mφs), whose protumoral activity is potently enhanced by SP cell-secreted soluble factor(s). Finally, coexpression of ECM-, iron-, and Mφ-related genes is found to be predictive of glioma patients' outcome. Our polymer-based approach reveals the intrinsic capacities of GSCs, to adapt the environment to organize a self-advantageous microenvironment niche, for their maintenance and expansion, which redefines the current concept of anti-CSC niche therapy and has the potential to accelerate cancer therapy development. Stem Cells 2016;34:1151-1162.