Peripheral blood chimerism after competitive transplantation of limiting dilutions of CD45⁺ liver SP tip cells. (A) Average 3-month blood chimerism arising from competitive transplantation of 200, 100, 50, or 10 purified CD45⁺ liver SP tip cells (LiSP) (n = 4 per group; error bars represent SEM). (B) Peripheral blood FACS analysis from a recipient in each group. CD45.1⁺/CD45.2^– events illustrate long-term blood reconstitution from varying doses of purified liver-derived cells. CD45.2⁺/CD45.1^– events arise from 2 × 10⁵ transplanted unfractionated competitor bone marrow cells or residual recipient cells that survived lethal irradiation. Numbers in dot plots represent percentage of cells within each gate.