Figure 1.

α4 and α5 function in freshly isolated or ex vivo expanded SRC. The percentage of human CD45⁺ cells was measured in bone marrow cells of recipient mice transplanted 6 weeks previously with 100–150×10³ uncultured cord blood CD34⁺ cells (A) or their expansion product (B) after short-term culture in stem cell factor, thrombopoietin, Fit-3 ligand, interleukin-6 and granulocyte colony-stimulating factor. The contribution of α4 and α5 integrins to bone marrow repopulation was determined by incubating cells with neutralizing monoclonal antibodies P4C2 (anti-α4, triangles) or P1D6 (anti-α5, squares) prior to transplantation. Control cells were incubated with anti-CD34 (circles). Solid symbols indicate the mean ± SEM engraftment levels in each experimental condition (n=3 independent experiments of one to three mice per group). *p<0.05 compared to transplantation of control cells.