Immunohistochemical expression of stem cell, endothelial cell, and chemosensitivity markers in primary glioma spheroids cultured in serum-containing and serum-free medium

OBJECTIVE: To investigate the influence of serum-free medium (SFM) supplemented with epidermal growth factor and basic fibroblast growth factor compared with conventional serum-containing medium (SCM) on the phenotype of organotypic primary spheroids from seven gliomas. METHODS: Paraffin sections of the original surgical specimens, primary glioma spheroids, and U87 derived spheroids were stained immunohistochemically with the stem cell markers CD133, podoplanin, Sox2, Bmi-1, and nestin; the endothelial cell markers CD31, CD34, and Von Willebrand Factor (VWF); the chemosensitivity markers P-glycoprotein and tissue inhibitor of metalloproteinases-1 (TIMP-1); and glial fibrillary acidic protein, neural cell adhesion molecule CD56, and the proliferation marker Ki67. RESULTS: Scoring of the immunohistochemical stainings showed that the expression of CD133 and all other markers included was preserved in primary spheroids, confirming the in vivo-like nature of these spheroids. Spheroids in SFM better mimicked the in vivo phenotype with significantly more CD133, CD34, VWF, P-glycoprotein, TIMP-1, and Ki67 compared with SCM. CONCLUSION: In this first study of the influence of SFM on primary glioma spheroids, the conditions favored an in vivo-like phenotype with increased expression of CD133. More vascular structures were found in SFM, suggesting that the close relationship between blood vessels and tumor stem-like cells was better preserved in this medium.