Apotransferrin decreases migration and enhances differentiation of oligodendroglial progenitor cells in an in vitro system

We have previously shown that a single intracranial injection of apotransferrin (aTf) in neonatal rats produces an accelerated mylinogenesis and increases the expression of certain myelin proteins such as myelin basic protein (MBP). In the present work, we studied the effects of aTf upon oligodendrocyte progenitor cell (Opc) cultures. In the presence of aTf, cells developed a multipolar morphology and showed an increased expression of O₄, MBP, O₁ and myelin-associated glycoprotein compared to controls. Migration studies using the agarose drop assay showed that aTf strongly inhibited OPc migration. This effect was not observed when an antibody against the transferrin receptor was added. The expression of two cell adhesion molecules, neural cell adhesion molecule (NCAM), N-cadherin and of polysialylated NCAM (PSA-NCAM) was evaluated by immunocytochemistry and by Western blot. Although NCAM expression did not change, there was a significant increase in N-cadherin expression and a decrease in PSA-NCAM in the aTf-treated cells. Time lapse studies of the expression of PSA-NCAM as an indicator of migration and of MBP as a marker of differentiation showed that in the cultures treated with aTf there is first a decrease in the percentage of cells expressing the former molecule which is followed by an increase in the percentage of cells expressing MBP. These results suggest that aTf added in vitro to cultured OPcs inhibits first their migration and then enhances their differentiation. Copyright