CD133+ cell content does not influence recovery time after hematopoietic stem cell transplantation

Infusion of an adequate dose of CD34+ mononuclear hematopoietic stem cells (HSCs) is the single most important variable to assure success in hematopoietic grafting. CD133+ HSCs constitute the CD34+ subgroup with higher differentiation potential. The number of granulocyte-colony-stimulating factor (G-CSF)-mobilized CD133+ HSCs administered during hematopoietic grafting and its relationship with the number of days needed to regain hematopoiesis was determined.

Thirty-eight patients with malignant hematologic diseases who received an autologous (n = 15) or allogeneic (n = 23) HSC transplant were prospectively evaluated. G-CSF was administered for 5 days at 10 microg/kg/day. Hematopoietic progenitors were recovered from peripheral blood on day 5 by leukopheresis. CD34+ and CD133+/CD34+ cell populations were quantified by flow cytometry; the number of days to hematologic recovery was documented.

A median dose of 4.56 x 10(6)/kg CD34+ HSCs (range, 1.35 x 10(6)-14.6 x 10(6)) was recovered and transplanted; of these grafted cells, a median 3.25 x 10(6) were also CD133+ (range, 1.25 x 10(6)-14.3 x 10(6)). In the autologous group, the median number of days to reach a platelet (PLT) count of 20 x 10(9)/L or greater was 12, and 15 days to obtain a neutrophil count of 0.5 x 10(9)/L or greater; in the allogeneic group 13 and 16 days, respectively, were required (p > 0.05). A median 76.5% of G-CSF-mobilized CD34+ HSCs coexpressed the CD133+ antigen (range, 23.1-97.9).

A higher number of CD133+/CD34+ HSCs in the graft was not clearly associated with a shorter neutrophil or PLT recovery time in either allogeneic or autologous recipients.