SDF-1–induced transendothelial migration of human CD34⁺ cells.

(A) Up-regulation of VCAM-1 (upper panels) and ICAM-1 (lower panels) by TNF-α on HUVECs or MBA-2.1 cells. Isotype control (IC); untreated cells (U); and TNF-α–treated cells (TNF-α) were stained with antibodies to VCAM-1 or ICAM-1. (B) CD34⁺ cells were incubated with neutralizing antibodies to LFA-1, VLA-4, VLA-5, or all together prior to migration through TNF-α preactivated endothelial cells toward SDF-1. (C) Migrating (M) and nonmigrating (NM) cells through MBA-2.1 toward SDF-1 were stained with antibodies to CD34 and CD38. (D) Percent engraftment by migrating (M) and nonmigrating (NM) cells in the murine bone marrow 1 month following transplantation, quantified by FACS analysis using antibodies to human CD45. Each dot represents 1 mouse. Numbers and bars indicate the engraftment averages plus or minus SE. (*Indicates P < .05.) (Experiment I [E I]) The presence of human progenitors in the bone marrow of mice transplanted with migrating (M) or nonmigrating (NM) cells. The shaded square indicates colony forming unit–granulocyte/macrophage (CFU-GM) cells; the open square indicates burst forming unit–erythroid (BFU-E), and the solid square indicates multilineage colony (CFU-GEMM). (E II) The levels of human lymphoid CD45⁺/CD19⁺ pre–B cells in the bone marrow of mice transplanted with migrating (M) cells.