Reduced homing capacity of hematopoietic progenitors generated in vitro. Lethally irradiated mice were transplanted with ∼10⁸ PKH26-labeled normal BM cells or ∼10⁷PKH26-labeled progeny of unfractionated or Sca-1⁺c-kit⁺Lin^- BM cells generated after 9 days of expansion in hematopoietic growth factors (see Table 1 for details). Three hours later, PKH26⁺ cells that had homed to the BM (□) or spleen (▪) were quantitated by flow cytometry and isolated by FACS for CFC assays. Shown are the mean ± SEM percent recovery of donor-derived cells (left) and CFCs (right) per organ.