P03.02IN SITU ORGANOTYPIC SLICE CULTURE MIGRATION MODEL TO DISSECT INFILTRATIVE FROM STATIONARY HUMAN BRAIN TUMOR INITIATING CELLS.

Glioblastomas (GBM) are highly malignant brain tumors, hallmarked by infiltrating growth of tumor cells. Brain Tumor Initiating Cells (BTIC) may initiate GBM pathogenesis according to recent publications. In particular the subventricular zone and hippocampus are areas where BTICs may arise and migrate to distinct areas to initiate the tumor bulk via differentiation into the glial linage. As a valuable tool an in situ model of organotypic brain slice cultures is utilized to visualize and analyse migration and invasion in a setting that simulates normal brain tissue conditions. This method allows the inoculation of tagged BTIC in the hippocampal region of fresh brain slice cultures from newborn rats (P8-12), and to monitor tumor cell invasion for up to three weeks. During this process the original cell population divides into different subpopulations: a stationary that proliferates at the implantation site, and an infiltrating one. Stationary and infiltrating cells differ in morphology and behaviour. In order to reveal why an initial cell population separates into subpopulations, a method was developed to microdissect single cells from the slices after an inoculation time of up to three weeks. cDNA libraries were generated for subsequent microarray analysis to compare the subgroups regarding gene expression profiles of genes associated with e.g. proliferation, invasion, cell-cell contacts, and stemness. Besides the different phenotypic appearance of the subpopulations, the genetic pattern of cells from the subpopulations determined by microarray analysis should unveil genes driving tumor invasion. These newly identified targets will be further characterized and regulated to manipulate the behaviour of BTICs.