DIFFERENTIATION AND PROLIFERATION - 2 POSSIBLE MECHANISMS FOR THE REGENERATION OF OLIGODENDROCYTES IN CULTURE

Two populations of oligodendrocytes exist in newborn mouse brain cell cultures: a population which expresses galactocerebroside (GC) and a further differentiated one which appears later and expresses both GC and myelin basic protein (MBP). The same culture system was used to find out: whether precursors of GC+ oligodendrocytes express GC; whether precursors of oligodendrocytes continue to differentiate during development in vitro; and whether immunocytochemically identified oligodendrocytes expressing GC or both GC and MBP are able to proliferate. The GC+ oligodendrocyte population was completely eliminated by complement-dependent antibody-mediated cytotoxicity at day 14 in vitro. The presence of GC+ and MBP+ oligodendrocytes was investigated by indirect immunofluroescence before, 18 h after, 2 days after and 7 days after cytotoxicity. Seven days after cytotoxicity 66% of the GC+ oligodendrocytes reappeared in culture, but only 16% of the MBP+ oligodendrocytes reappeared. The precursors of the oligodendrocytes apparently do not express GC. Between the 14th and the 21st day of culture, the GC negative precursors of oligodendrocytes continue to differentiate. The proliferative capability of immunocytochemically identified GC+ and GC+MBP+ oligodendrocytes was investigated by [3H]thymidine autoradiography. Both populations are capable of proliferation. The percentage of proliferating GC+ oligodendrocytes is 6 times higher than that of GC+MBP+ ones. These data indicate a regenerative potential of oligodendrocytes.