Single-cell sorting was performed by two-step sorting. Cord blood CD34⁺CD38⁺c-kit⁺ cells, CD34⁺CD38⁺c-kit⁻ cells, CD34⁺CD38⁻c-kit⁺ cells, and CD34⁺CD38⁻c-kit⁻ cells were individually sorted in 5 mL-tubes by the FACStar^plus flow cytometer. Then, cells in each group were resorted into the individual wells of a 96-well culture plate containing SCF or SCF + TPO. A half medium exchange was performed every week. After 3 weeks, the constituent cells in each well were identified under microscopic visualization and/or on the cytospin preparations stained with May-Grünwald Giemsa. The results shown are from one representative experiment of three. Similar results were obtained in the other two experiments.

Abbreviations: n, neutrophilic cells; m, macrophages; mast, mast cells; nmast, neutrophilic cells/mast cells; undifferentiated, undifferentiated cells which disintegrated without any terminal differentiation until 3 weeks.