CD34 and leukemia: A single-arm first-in-human clinical trial enrolling 35 patients with high-risk leukaemia has shown that transplantation with >5.0 × 106 CD34+ cells/kg and a defined dose of naive CD45RA T-cell-depleted peripheral blood stem cell (PBSC) grafts after a total body irradiation (TBI)-containing myeloablative conditioning regimen translates into prompt engraftment [28] (Table 2).