CD133 + Cell Selection Is an Alternative to CD34 + Cell Selection for Ex Vivo Expansion of Hematopoietic Stem Cells

Abstract

CD133 is a new stem cell antigen that may provide an alternative to CD34 for the selection and expansion of hematopoietic cells for transplantation. This study compared the expansion capacities of CD133⁺ and CD34⁺ cells isolated from the same cord blood (CB) samples. After 14 days culture in stroma-free, serum-free medium in the presence of stem cell factor (SCF), Flt3-1, megakaryocyte growth and development factor (MGDF), and granulocyte colony-stimulating factor (G-CSF), the CD133⁺ and CD34⁺ fractions displayed comparable expansion of the myeloid compartment (CFC, LTC-IC, and E-LTC-IC). The expansion of CD133⁺ CB cells was up to 1262-fold for total cells, 99-fold for CD34⁺ cells, 109-fold for CD34⁺ CD133⁺ cells, 133-fold for CFU-GM, 14.5-fold for LTC-IC, and 7.5-fold for E-LTC-IC. Moreover, the expanded population was able to generate lymphoid B (CD19⁺), NK (CD56⁺), and T (CD4⁺ CD8⁺) cells in liquid or fetal thymic organ cultures, while expression of the homing antigen CXCR4 was similar on expanded and nonexpanded CD133⁺ or CD34⁺ cells. Thus, the CD133⁺ subset could be expanded in the same manner as the CD34⁺ subset and conserved its multilineage capacity, which would support the relevance of CD133 for clinical hematopoietic selection.