MBRS-44. MODELLING THE BRAIN/CSF INTERFACE IN MEDULLOBLASTOMA

The pathways involved in medulloblastoma dissemination and metastasis remain elusive. Invasive cells must travel from brain parenchyma to other regions in the brain/spine via the cerebrospinal fluid (CSF), where they can form laminar metastases on the surface of the leptomeninges, or nodular tumours. This project aims to develop a 3D culture model representing the basement membrane interface between the brain parenchyma and the CSF in order to isolate migrating cells, and identify gene expression changes that predict and control cell migration. Basement membrane extract (BME) or its major component collagen IV were used to model the basement membrane, and a hyaluronic acid gel was used to model the brain parenchyma. The 3D culture conditions in BME were optimised for a panel of group 3 and group 4 medulloblastoma cell lines. Laminar coating was observed when cells were seeded on top of BME, whereas embedded cells formed large nodules. This appeared to be induced by factors in the secretome of cell clusters, since cell clusters preferentially migrated towards each other rather than along a chemokine gradient. Trans-well migration assays across collagen IV, however, showed that cell lines migrated in response to serum, and a cell line-dependent response to soluble factors was observed. The aim of our model is to isolate RNA from cells as they migrate through the basement membrane interface, allowing the underlying mechanism to be studied by RNA Seq.