C6 glioma-astrocytoma cell and fetal astrocyte migration into artificial basement membrane: a permissive substrate for neural tumors but not fetal astrocytes.

Cortically homografted C6 glioma-astrocytoma cells both invade the rat host brain as a mass and migrate as individual cells. In contrast, fetal astrocytes derived from homografted whole pieces of fetal cortex migrate only as individual cells throughout the brain of the rat but are not capable of invasion. Our experiment explored the migratory capacity (over 7 days) of cultured purified fetal astrocytes and C6 cells after seeding 10(6) cells on a hydrated artificial basement membrane wafer (Matrigel). The artificial basement membrane wafer was not a suitable substrate for the growth of cultured fetal astrocytes. In contrast, C6 cells migrated as individual cells from the surface of the wafer into the substrate. Individual C6 cells migrated 1.8 mm in the first 4 days and then ceased migration. The C6 cells were observed at the base of a digestion tube that extended from and was open to the surface of the wafer. At 3 days, micropockets were observed to form around each C6 cell at the base of each tube. By 7 days, the majority of pockets observed were large and contained several C6 cells. These multiple cell groups appeared to be progenitors of tumor masses. These data indicate that C6 glioma-astrocytoma cells, which in vivo appear to be a model for glioblastoma multiforme, primarily migrate as individual cells through artificial basement membrane and secondarily form tumor masses. Progenitor tumor masses form by coalescence of individual C6 cell micropockets or the division of a single cell in an individual micropocket.