Transient production of donor hemoglobin following CD31⁺ Sca-1^– cell transplantation. (A) Donor and host hemoglobin levels (lanes D and H) were evaluated by electrophoresis following transplantation of either 500 CD31⁺ KSL cells or 10 000 CD31⁺ Lin^– c-kit⁺ Sca-1^– cells (Sca-1^– cells). (B) The percentage of donor versus host hemoglobin was determined in recipients of either 500 CD31⁺ KSL cells (□) or 10 000 CD31⁺ Lin^– c-kit⁺ Sca-1^– cells (▪) between 2 to 12 weeks after transplantation. Combined results from 3 experiments are shown. Error bars indicate SEM; *P ≤ .04, **P ≤ .005, ***P ≤ .0005; ND indicates not detected, level of detection ≥ 5%.