Comparison of the Phenotype and Clonogenicity of Normal CD34 + Cells from Umbilical Cord Blood,Granulocyte Colony-Stimulating Factor-Mobilized Peripheral Blood,and Adult Human Bone Marrow

Abstract

Bone marrow (BM) is most frequently used to transplant hematopoietic progenitor cells, but umbilical cord blood (UCB) and mobilized peripheral blood (PB) provide alternative sources of progenitor cells for transplantation. To study whether the clonogenicity and phenotype of progenitor cells vary between the compartments, CD34⁺ cells from UCB, mobilized PB, and BM were analyzed for in vitro colony formation and characterized by immunophenotyping for several lineage-associated and maturation-related cell surface molecules. We found that circulating CD34⁺ cells, either from PB after granulocyte colony-stimulating factor (G-CSF) mobilization or from UCB, contained a large proportion of cells (86-96%) with myeloid cell-associated molecules (CD33 and CD13) and clonogenic cells (colony-forming unit-granulocyte-macrophage and burst-forming unit-erythrocyte) in excess of BM CD34⁺ cells. Further, UCB and PB CD34⁺ cells contained ≥3% cells with a phenotype associated with immature (HLA-DR^- and CD38^-) progenitor cells, which was comparable to what is found among BM CD34⁺ cells. The proportion of CD34⁺ cells in UCB expressing the B cell-associated molecules (CD10 and CD19) was comparable to that found in mobilized PB (≤5%) but significantly lower than for BM CD34⁺ cells (19-24%). Further, we observed a higher proportion of CD34⁺ cells expressing the T cell-associated molecule CD7⁺ in UCB (7%) compared with both PB and BM (3-4%). In general, circulating CD34⁺ cells, either from UCB or G-CSF-mobilized PB, display largely the same phenotypic profile and clonogenicity, being different from resident CD34⁺ cells in BM.