CG‐4, A new bipotential glial cell line from rat brain, is capable of differentiating in vitro into either mature oligodendrocytes or type‐2 astrocytes

Abstract We have established a permanent cell line (CG‐4) of rat central nervous system glial precursors from primary cultures of bipotential oligodendrocyte‐type 2‐astrocyte (O‐2A) progenitor cells, which were kept proliferating with the mitogen(s) secreted by the neuronal B104 cell line. The CG‐4 cells have a normal karyotype and display the properties of normal O‐2A cells. CG‐4 cells can be propagated in serum‐free culture medium supplemented with medium conditioned by B104 cells for unrestricted periods of time as O‐2A cells, characterized by the presence of the A2B5 surface marker and the absence of markers specific for Oligodendrocytes (galactocerebroside, myelin basic protein) or type 2‐astrocytes (glial acidic fibrillary protein). bFGF and PDGF are potent mitogens for CG‐4 cells and their combination can substitute for the B104‐derived mitogen(s). CG‐4 cells are capable of differentiating into either Oligodendrocytes or type 2‐astrocytes. Differentiation into Oligodendrocytes occurs after withdrawal of the mitogen. Replacement of the mitogen with fetal calf serum (20%), in contrast, induces 50% of the CG‐4 cells to differentiate into type 2‐astrocytes. Pure cultures of Oligodendrocytes or type 2‐astrocytes can be generated in substantial amounts from CG‐4 cells and maintained for several weeks in medium containing 5% fetal calf serum.