Mobilization of CD34~+CD38~- hematopoietic stem cells after priming in acute myeloid leukemia

AIM: To evaluate quantitatively and qualitatively the different CD34⁺ cell subsets after priming by chemotherapy granulocyte colony-stimulating factor (± G-CSF) in patients with acute myeloid leukemia.METHODS: Peripheral blood and bone marrow samples were harvested in 8 acute myeloid leukemia patients during and after induction chemotherapy. The CD34/CD38 cell profile was analyzed by multi-parameter flow cytometry. Adhesion profile was made using CXC chemokine receptor 4 (CXCR4) (CD184), VLA-4 (CD49d/CD29) and CD47.RESULTS: Chemotherapy ± G-CSF mobilized immature cells (CD34⁺CD38⁻ population), while the more mature cells (CD34⁺CD38^low and CD34⁺CD38⁺ populations) decreased progressively after treatment. Circulating CD34⁺ cells tended to be more sensitive to chemotherapy after priming with G-CSF. CD34⁺ cell mobilization was correlated with a gradual increase in CXCR4 and CD47 expression, suggesting a role in cell protection and the capacity of homing back to the marrow.CONCLUSION: Chemotherapy ± G-CSF mobilizes into the circulation CD34⁺ bone marrow cells, of which, the immature CD34⁺CD38^– cell population. Further manipulations of these interactions may be a means with which to control the trafficking of leukemia stem cells to improve patients’ outcomes.