A subset of 5 of 9 mice who received only costimulation blockade (no busulfan) developed significant RBC chimerism.

Lane 1 shows a representative mouse without engraftment, with only human β-sickle hemoglobin. Lane 2 shows a representative mouse 3 months after transplantation with RBC chimerism, having both recipient (human β-sickle hemoglobin) and donor (mouse major and minor β-hemoglobin alleles) RBCs. Hu indicates human; Mu, murine.