In vitro characterization of a murine oligodendrocyte precursor cell line (BO-1) following spontaneous immortalization.

The understanding of oligodendrocyte differentiation is crucial for designing therapies of demyelinating diseases. Oligodendrocyte precursor cells are of particular interest in this context, because of their remyelinating potential. Permanent cell lines, which are a versatile tool for studying oligodendrocyte physiology, have been so far mainly established from the rat CNS. In the present study, we describe a novel murine oligodendrocyte precursor cell line (BO-1) established by spontaneous immortalization using light microscopy, immunocytochemical phenotyping and genetic analysis. BO-1 cells displayed a bi- to multipolar morphology and expressed early oligodendrocytic lineage markers, such as A2B5 and NG-2. Expression of pre-oligodendrocyte (O4, CNPase) and mature oligodendrocyte markers (e.g. myelin basic protein) was found in about 30% and 1.5% of the cells, respectively. Addition of serum, known to promote type-2 astrocyte differentiation, significantly increased the number of GFAP-positive cells, while thyroid hormones, (T3/T4) known to foster oligodendrocyte differentiation, did not substantially alter the antigenic and gene expression of myelin markers. This deficiency might be related to the high intrinsic proliferation rate of BO-1 cells that was unaltered upon removal of mitogenic factors. Expression of O4 and CNPase in BO-1 cells could be significantly increased by co-culture with primary astrocytes suggesting that the differentiating potential of BO-1 cells was influenced by environmental factors and may have to be fully explored in future studies. In summary, the novel murine BO-1 cell line shares several characteristics with oligodendrocyte precursor cells but displays a restricted differentiation into mature oligodendrocytes.