Comparative analysis of proliferative potential and clonogenicity of MACS-immunomagnetic isolated CD34+ and CD133+ blood stem cells derived from a single donor.

A novel stem cell marker prominin-1 (CD133) has been shown to be expressed on a subpopulation of CD34⁺ haematopoietic stem and progenitor cells. The aim of this study was to compare in parallel commercially available CD34⁺ and CD133⁺ isolation methods based on paramagnetic bead-coupled antibodies using clinical-grade samples of mobilized peripheral blood from 10 individual healthy donors under identical conditions. The CD133 negative fraction from the first selection was used for CD34⁺ enrichment to obtain an additional CD34⁺/CD133⁻ population. Although no significant difference in total cell expansion between cells isolated from the three procedures was observed in a 7-day cytokine-driven suspension culture, the long-term culture-initiating cell assay demonstrated that cells derived by CD34⁺ isolation contain less primitive progenitors than those isolated based on CD133⁺ selection. Interestingly, CD34⁺-enriched progenitors, especially the CD34⁺/CD133⁻ fraction, contained a significantly higher proportion of erythroid colony-forming cells, whereas the highest content of myeloid colony-forming cells was concentrated in the CD133⁺ selected cells. These subtle differences between CD34⁺ and CD133⁺ immunomagnetic selection will have to be explored for their potential clinical relevance. [ABSTRACT FROM AUTHOR]