Effect of varying culture conditions on homing of CD34⁺ cells in NOD/SCID mice. (A) Freshly isolated CD34⁺ cells (fresh) were compared with cells stimulated in the presence or absence of IL-3, as indicated. (B) CD34⁺ cells were cultured for 4 days in SCF, FL, IL-3, and IL-6 with retronectin (ctl Rn) or without it (ctl). Some cells were washed and replated for another 2 days in the same cytokines (+2d) or on retronectin (+2d Rn) or with SDF (+2d SCF, TPO, SDF-1), as indicated. At the end of the culture period, cells were washed and injected into conditioned animals (2 × 10⁶ cells/animal), and 24-hour BM homing of CFCs was determined. Data are displayed as for Figure 2B.