Maintenance of Stemlike Glioma Cells and Microglia in an Organotypic Glioma Slice Model.

Abstract

The therapeutic resistance of gliomas is, at least in part, due to stemlike glioma cells (SLGCs), which self-renew, generate the bulk of tumor cells, and sustain tumor growth. SLGCs from glioblastomas (GB) have been studied in cell cultures or mouse models, whereas little is known about SLGCs from lower grade gliomas. To compare cell and organotypic slice cultures from GBs and lower grade gliomas and study the maintenance of SLGCs. Cells and tissue slices from astrocytomas, oligodendrogliomas, oligoastrocytomas, and GBs were cultivated in (1) serum-free medium supplemented with the growth factors epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), (2) medium containing 10% serum plus EGF and bFGF (F+GF medium), or (3) medium containing 10% fetal calf serum (F medium). Maintenance of cells and cytoarchitecture was addressed, using several candidate SLGC markers (Nestin, Sox2, CD133, CD44, CD49f/integrin α6, and Notch) as well as CD31 (endothelial cells), ionized calcium-binding adapter molecule 1 (microglia), and vimentin. Cell vitality was determined. SLGCs were present in tissue slices from lower and higher grade gliomas. Preservation of the cytoarchitecture in slices was possible for >3 weeks. Maintenance of SLGCs required the presence of EGF/bFGF in cell and slice cultures, in which F+GF appeared superior to N medium. Constraints were observed regarding the preservation of the microglia but not of the endothelial cells. Maintenance of the microglia was improved by addition of the cytokine macrophage colony-stimulating factor. Medium supplemented with serum and growth factors EGF, bFGF, and macrophage colony-stimulating factor permits the preservation of SLGCs and non-SLGCs in the original glioma microenvironment.