CD34 and CXCR4 expression on freshly isolated versus cytokine-expanded CD34⁺-enriched cord blood cells. (A) Representative dot blot of CD34 and CXCR4 expression on freshly isolated CD34⁺ cells and CD34⁺ cells expanded in a cocktail of cytokines (see “Materials and methods”) for 4 days. Freshly isolated and expanded CD34⁺ cells were stained using CD34-FITC, CXCR4-APC monoclonal antibodies (mAbs) and analyzed by multivariant flow cytometry. Gates were set on the basis of cell staining with matched-isotype control mAbs. Similar results were obtained in 8 other experiments performed independently. (B) Representative dot blot showing expression of CD34 and CXCR4 on ex vivo–expanded CD34 cells after 24 hours of culture in cytokine cocktail alone (medium) or along with TGF-β1 (0.5 ng/mL), SDF-1 (200 ng/mL), or the combination of SDF-1 (200 ng/mL) + TGF-β1 (0.5 ng/mL). CXCR4 expression on CD34⁺ cells is presented as mean ± SD of 3 independent experiments. MFI indicates mean fluorescence intensity.