CHARACTERIZATION AND PHENOTYPIC ANALYSIS OF DIFFERENTIATING CD34(-MARROW CELLS IN LIQUID CULTURE() HUMAN BONE)

Our current understanding of human haematopoietic stem cell biology is based in part on the characterization of human CD34(+) bone marrow ce ll differentiation in vitro. CD34 is highly expressed on early stem ce lls and haematopoietic progenitor cells with clonogenic potential and is gradually lost during differentiation and commitment. However, CD71 (transferrin receptor) is expressed at low levels on early stem cells and generally increases during haematopoietic progenitor cell prolife ration. We reasoned that the combination of these surface markers woul d provide a useful framework for the simultaneous analysis of multiple lineage differentiation of CD34(+) haematopoietic progenitor cells in liquid culture, In this report, we identify the phenotype of distinct subpopulations of myeloid, erythroid and lymphoid cells in liquid sus pension culture using differential expression of CD34 vs. CD71 in comb ination with specific lineage markers. Freshly isolated human CD34(+) bone marrow cells were introduced into suspension culture and monitore d over a 6-d period using 3-colour flow cytometry. This is the first d emonstration that differential expression of CD34 vs. CD71 can be used to simultaneously monitor differentiation of multiple haematopoietic cell lineages in liquid suspension culture, facilitating the study of cytokine-, drug- or chemical-induced alterations in haematopoietic pro genitor cell differentiation in vitro.