A novel model of glioma cell invasion using organotypic brain slice culture.

A novel model of glioma cell invasion was established by using an organotypic culture of rat brains. Brain slices prepared from 2-day-old rat neonates were maintained in a culture at the interface between air and the culture medium. The slices were placed on double-layered membranes consisting of a polycarbonate membrane with 8-microm pores and a membrane with 0.4-microm pores. The organotypic cytoarchitecture of the cultured brain slices remained well preserved, and the neuronal viability was kept intact for over 2 months. When C6 glioma spheroids were cocultured with the brain slices, the tumor cells migrated in a scattered fashion around the spheroids. Exogenous L1 or glioma motility factor I strongly stimulated the cell migration, whereas fibronectin, tenascin, and glioma motility factor II had little or no effect. When C6 glioma cells placed on the brain slices were incubated while being stimulated by L1-transfected fibroblast cells for 2 days, many more tumor cells invaded and reached the bottom of the upper membrane. This L1-stimulated glioma cell invasion into brain slices was significantly inhibited by an anti-L1 antibody. Our novel invasion model, which mimics the in vivo conditions of the central nervous system, may make it possible to analyze actual events of glioma cell invasion in normal brains in situ.