Assessments of migration of CD34⁺hematopoietic progenitors.

(A) Migration of freshly isolated (left) and GM-CSF–stimulated (right) CD34⁺ hematopoietic progenitors toward interferon (IFN) γ–inducible protein 10 (γIP-10) (open bars), monokine induced by IFN-γ (Mig) (black bars), and chemokine stromal cell-derived factor 1α (SDF-1α) (gray bars). All results are expressed as the mean ± SD percentage of input cells that migrated (n = 5) and are based on triplicate determinations of chemotaxis for each concentration of chemokines. An asterisk indicates a significant difference from the medium control (P < .03, except in one case, in whichP < .04). (B) Checkerboard analysis for GM-CSF–stimulated CD34⁺ hematopoietic progenitors toward γIP-10 (right) and Mig (right). Chemokines were applied in the upper chamber, the lower chamber, or both. The concentrations of chemokines applied in the lower chambers were 0, 1, 10, 100, and 1000 ng/mL (indicated as 1, 2, 3, 4, and 5, respectively). The data are from one representative experiment of 2 performed. (C) Specific chemotactic activity of γIP-10 (right), Mig (middle), and SDF-1α (right) for subtypes of colony-forming, GM-CSF–stimulated CD34⁺hematopoietic progenitors from cord blood. CD34⁺ cells attracted to different chemokines at the indicated concentrations were assayed for colony-forming cells and the results expressed as the mean ± SD percentage of input cells that migrated (n = 3). Open bars, black bars, and gray bars indicate burst-forming units–erythroid, colony-forming units–granulocyte-macrophage, and colony-forming units–granulocyte-erythroid-macrophage-megakaryocyte, respectively. An asterisk indicates a significant difference from the medium control (P < .04). (D) Flow cytometry analysis for CD34⁺ cells before (left) and after (right) migration toward γIP-10. The cells were dual stained; percentages indicate positive or negative cells.