Fig. 6

Immunohistochemical detection of tumor cells in the brain slice cultures. After siramesine exposure of organotypic corticostriatal brain slice cultures being implanted beforehand with spheroids, these co-cultures were fixed, paraffin embedded, sectioned (3 μm) and immunohistochemically stained with anti-human specific CD56 in order to identify the tumor cells. For comparison these co-cultures were scanned to monitor invasion and cell death during exposure as illustrated in Fig. 5. a Invasion of CD56 positive human tumor cells from T78 and T86 spheroids into the surrounding brain tissue was observed in 3 μm histological sections in all cultures and at all concentrations of siramesine. b No difference in spheroid size, invasion area and distance was found between control cultures and cultures being exposed to different concentrations of siramesine. The “invasion area” was defined as the area of cells, which had detached from the spheroids and invaded into the brain tissue. The “invasion distance” was defined as the maximal distance measured to an invasive cell. Control cells received culture medium or DMSO (images not shown) both without siramesine. Scalebar 100 μm (a). Data are displayed as mean values ± SEM, and **P < 0.01, ***P < 0.001 were assessed by one-way ANOVA