Fig. 6. Extent of CB-derived neural cell differentiation. Quantification of the extent of neuronal, astrocytic and oligodendrocytic differentiation in cultures grown for 4 days in differentiation-promoting conditions. White bars: neurobasal medium (NM) supplemented with 10% FCS; dotted bars: NM with 10% FCS plus 0.5 µM of RA; striped bars: NM, 10% FCS, 0.5 µM RA with addition of 10 ng/ml BDNF; grey bars: cells after seeding on monolayer of rat primary cortical culture grown for 4 days in DMEM supplemented with 10% FCS. Note that promotion of differentiation was best in co-culture (grey bars). In pure, CB-derived cell systems, the presence of RA was decisive for neuronal differentiation, whereas additional supplementation with BDNF promoted mainly astrocytes, with a significant retention of oligodendrocytes. A subpopulation of CB-derived cells growing in a monolayer before clone formation was found to be negative for all investigated antigens. The results are expressed as the mean±s.d. of cell number from nine independent cultures (three parallel experiments from three separate cord blood preparations).