GLIOBLASTOMA CELLS DO NOT INTRAVASATE INTO BLOOD-VESSELS

GLIOBLASTOMA IS VERY rarely found outside the central nervous system. The ability of rat C6 glioblastoma cells to intravasate into central n ervous system and pial blood vessels is tested using a rat homograftin g model and two in vitro models. In vivo, scanning electron microscopy demonstrates that upon grafting C6 cells into implantation pockets in rat cortex, blood vessels can be spared in large digestion cysts form ed in host brain parenchyma. Immunocytochemistry of the grafted rat co rtex reveals that the glioblastoma cells are upon the blood vessel bas ement membrane, surrounded by the extracellular matrix material, fibro nectin. The endothelial cells of the blood vessel are inside the lamin in and fibronectin, and there were areas of endothelial cell hyperplas ia. C6 cells are not observed inside blood vessels. In vitro, C6 cell cultures seeded with blood vessels from fresh rat pia exhibit the same relationship of the C6 glioblastoma cells to the blood vessel as thos e in the other models. The C6 cells migrate upon the pial blood vessel basement membrane but do not intravasate into the blood vessel. To as certain whether structure and components of the blood vessel basement membrane are important factors in glioblastoma cell exclusion from blo od vessels, C6 cells are seeded upon artificial basement membrane hydr ated gel wafers. C6 cells migrate into the artificial basement membran e gel wafer by 1 day after seeding. These data indicate that glioblast oma cells are confined to the central nervous system by an inability t o pass through vital basement membrane.