Mobilization kinetics of CD133+ hematoprogenitor cells for hematopoietic grafting

BACKGROUND: Quantification of CD34+ mononuclear cells is the most important quality control measure for hematopoietic stem cell (HSC) transplantation. A fraction of CD34+ cells also express the CD133 antigen. These cells constitute a group of earlier, less-differentiated HSCs with a potentially higher capacity for engraftment. The correlation between total CD34+ peripheral HSCs and the fraction of these cells that coexpress CD133 was determined before and after automated collection by leukapheresis, as well as the effect of HSC CD133+ dose on hematopoiesis recovery.
STUDY DESIGN AND METHODS: Granulocyte–colony-stimulating factor mobilization of HSCs from the marrow to the peripheral blood (PB) of allogeneic and autologous donors was followed by automated collection through leukapheresis on the fifth day. Quantification of CD34+ and CD133+ cells was performed on PB before collection and in the hematopoietic graft (HG) by flow cytometry.
RESULTS: There was a significant correlation between CD133+ and CD34+ HSCs in the PB before collection and in the final product for grafting (r = 0.62 and 0.64; p < 0.01). CD34+ HSCs per µL in PB and the HG was the only variable that did not correlate (r = 0.18). CD34+/CD133+ correlation increased from 0.33 on PB to 0.94 on the leukapheresis product (p < 0.01). Time to recovery was not related to CD133+ HSCs infused.
CONCLUSION: There was a significant correlation of both number per µL and percentage of CD34+/CD133+ HSCs before and after collection for transplantation; number of CD133+ cells had no apparent clinical impact on time to hematopoiesis regeneration.