gms | German Medical Science

Objective: The survival rate of patients with malignant brain tumours is very poor. It is not known whether and how cells with stem cell features affect the growth of glioma or the success of chemotherapy and irradiation. We evaluated the presence of stem cell-like cells in different types of malignant glioma and analyzed their self-renewal in vitro.

Methods: Tumour cell lines were established from malignant glioma of the human brain. Cells were propagated in media containing fetal calf serum (FCS) or a serum substitute. Gene expression was studied by RT-PCR, western blot analysis and immunocytochemistry. We performed in situ double staining with antibodies directed against nestin and the glial fibrillary acidic protein (GFAP), respectively, to identify cells exhibiting a neural stem cell-like feature. GFAP expression in the absence of nestin is indicative of a glial, co-expression of microtubule-associated protein 2 (MAP2) and neurofilament (NF) or MAP2 and Tau of a neuronal phenotype. In addition, antibodies directed against oligodendrocytes, as well as mesenchymal or ectodermal cell derivatives were used in the study.

Results: Primary cultures of glioblastoma and gliosarcoma consisted of varying amounts of fibroblasts, myofibroblasts, astrocytes, neurons and other cell types. A large portion of the latter ones stained positive for both nestin and GFAP, indicating the presence of neural stem cell-like cells in malignant glioma. Moreover, up to 40% percent of the cells stained positive for NF, which is expressed in neurons of the peripheral and central nervous system and which has also been found in several tumours of the nervous system. When continuously grown in media containing FCS Nestin+/GAPF+ cells disappeared from the cultures. In contrast, growth in media containing a serum substitute and mitogens, a condition used for the propagation of adult neural stem cells, led to progressive enrichment of Nestin+/GFAP+ cells, which self-renewed and formed neurospheres.

Conclusions: Our data show that malignant glioma harbour different cell types, including cells which exhibit features of neural stem cells. The neural stem cell-like cells drastically responded to changes of the culture conditions, resulting in their disappearance and enrichment, respectively. This suggests that changes in the micro-environment of a glioma will influence its cellular composition and the growth of the neural stem cell-like cells.