The generation and properties of human macrophage populations from hemopoietic stem cells

Abstract: Information about the development and function of human macrophage lineage popu-lations, such as osteoclasts, is limited because of the lack of defined in vitro systems for their large-scale generation. Two M-CSF-containing cytokine cocktails were found under serum-free conditions to expand dramatically and to differentiate over time human CD34 hemopoietic stem cells into nonadherent and adherent macrophage popula-tions. These populations exhibited increasing de-grees of maturity over a 3-week period character-ized by morphology, surface marker expression (CD11b, CD86, CD64, CD14, and c-Fms), phago-cytic function, and gene-expression profiling using quantitative PCR and microarray analysis (princi-pal component analysis, k-means clustering, and gene ontology classification). As assessed by the last criterion, the adherent population obtained at 3 weeks from the one protocol tested had high simi-larity to the well-studied peripheral blood mono-cyte-derived macrophages. The one population tested could be induced to differentiate into osteo-clasts in the presence of M-CSF and receptor acti-vator of NF-B ligand, as judged by morphology, gene expression, and bone-resorbing ability. In ad-dition to the large numbers of macrophage lineage cells able to be produced, this replicating system may be suitable for the molecular analysis of mac-rophage lineage commitment and progression and for gene targeting and delivery. J. Leukoc. Biol