Figure 5.

Effect of DLK-1-overexpression on the haematopoiesis-supporting capacity of CB MSC. (a) Exemplarily co-culture of CD34⁺-cells on feeders of CB MSC and FACS-sorted CB MSC strongly overexpressing DLK-1 (CB MSC^{DLK  high}) in multiple independent wells (n = 4). Within 14 days, overexpression of DLK-1 did not have a beneficial effect on expansion rates of total cells, CD34⁺-cells or CFU. In accordance to former results for native CB MSC, only a weak expansion of total cells was observed, while amounts of total CD34⁺-cells as well as CFU slightly declined over time. (b) Expression levels of haematopoietic cytokines (IGF-2, IGFBP-1, SCF, SDF-1, THPO, ANGPTL-3) were analyzed by real time PCR exemplarily for a CB MSC line in native form, after induced overexpression of DLK-1 (CB MSC^DLK) as well as after further FACS-sorting for cells with high DLK-1 expression (CB MSC^{DLK  high}), respectively. No significant differences in expression levels could be detected and results were in accordance with former data, as presented in Figure 4(b).