EFFECTS OF CULTURE CONDITIONS ON GLIAL CELL DEVELOPMEN

Neuroepithelial cells give rise to the neural elements of the central nervous system, but the factors and cellular interactions that influence the commitment of cells to specific neural lineages are not well understood. I have used cultured non-neuronal process-bearing (PB) cells from neonatal rat cerebral cortices as a model to assess the influence of various culture conditions on the determination of cells as either astroglia or oligodendroglia. The expression of glial-specific markers by PB cells prepared and grown under various culture conditions was determined by immunocytochemistry with astroglial-specific anti-glial fibrillary acidic protein (GFAP) and oligodendroglial-specific anti-galactocerebroside (GC).;Post-separation plating density and serum content of culture medium influenced glial cell development in vitro. Increasing post-separation plating density was significantly associated (p < .001) with decreasing percentages of GFAP+ cells, increasing percentages of GC+ cells, and increasing percentages of non-stained cells. As the fetal calf serum content of growth medium was increased, the percentage of GFAP+ cells increased, and as the serum content was decreased, the percentage of GC+ cells increased. PB cells appeared to switch their phenotypic expression from GFAP+ in the presence of serum to GC+ in serum-free medium. This conclusion was supported by combined ('3)H-thymidine autoradiography/ immunocytochemistry and the observation of a small population of PB cells that co-expressed GFAP and GC. PB cells exhibited some plasticity in their phenotypic expression as cells grown for 9 days in serum-free medium were still responsive to the effects of serum, while cells grown for 6 days in serum were refractory to serum withdrawal.;This research has demonstrated the developmental plasticity of PB cells isolated from polygonal astroglia as they expressed GFAP in the presence of serum, and GC in serum-free medium. It is hypothesized that PB cells grown with polygonal astroglia may develop into oligodendroglia even in the presence of serum, suggesting a possible influence of polygonal astroglia on PB cell determination. This system should provide a useful model for the examination of other factors and cellular interactions that may influence the development of glial cells.