Durable, titratable WBC and RBC chimerism was produced in the sickle mice receiving transplants. (A) Increasing amounts of donor bone marrow yielded titratable WBC and RBC chimerism. Unmanipulated bone marrow cells from donor eGFP mice were transplanted into sickle recipients, and chimerism was determined at the terminal time point (6-10 months after transplantation). ▴ = percentage of donor WBCs, ▴ = percentage of donor Hb in the peripheral blood, respectively, for individual mice. (B) A wide range of RBC chimerism developed in the mice that received transplants. Shown is a representative hemoglobin electrophoresis with blood from animals that received transplants that demonstrates increasing amounts of donor Hb: From left to right, 0% (sickle control), 17% (no. 1582), 43% (no. 1550), 57.5% (no. 1636), 79% (no. 1630), 90% (no. 70), 100% (no. 62), and 100% (eGFP control). (C) Chimerism is stable over time. WBC chimerism was determined as the percentage of eGFP⁺/CD45⁺ cells in the peripheral blood. The average WBC chimerism over time for each of the 6 different treatment conditions is shown: ♦ = 1 × 10⁶ donor bone marrow cells, ▴ = 5 × 10⁶, ▵ = 10 × 10⁶, ▪ = 15 × 10⁶, □ = 20 × 10⁶, • = 20 × 10⁶ after pretreatment with 20 mg/kg busulfan (inset). For each bone marrow dose, n = 3-7. Error bars show SEM.