title: Human cord blood CD34+Pax-5+ B-cell progenitors: single-cell analyses of their gene expression profiles.
abstract: Circulating CD34(+) cells are used in reparative medicine as a stem cell source, but they contain cells already committed to different lineages. Many think that B-cell progenitors (BCPs) are confined to bone marrow (BM) niches until they differentiate into B cells and that they do not circulate in blood. The prevailing convention is that BCP transit a CD34(+)CD19(-)10(+) early-B-->CD34(+)CD19(+)CD10(+) B-cell progenitor (pro-B)-->CD34(-)CD19(+)CD10(+) B-cell precursor (pre-B) differentiation pathway within BM. However, populations of CD34(+)CD10(+) and CD34(+)CD19(+) cells circulate in adult peripheral blood and neonatal umbilical cord blood (CB) that are operationally taken as BCPs on the basis of their phenotypes, although they have not been submitted to a systematic characterization of their gene expression profiles. Here, conventional CD34(+)CD19(+)CD10(+) and novel CD34(+)CD19(+)CD10(-) BCP populations are characterized in CB by single-cell sorting and multiplex analyses of gene expression patterns. Circulating BCP are Pax-5(+) cells that span the early-B, pro-B, and pre-B developmental stages, defined by the profiles of rearranged V-D-J(H), CD79, VpreB, recombination activating gene (RAG), and terminal deoxynucleotidyl transferase (TdT) expression. Contrary to the expectation, circulating CD34(+)CD19(-)CD10(+) cells are essentially devoid of Pax-5(+) BCP. Interestingly, the novel CD34(+)CD19(+)CD10(-) BCP appears to be the normal counterpart of circulating preleukemic BCPs that undergo chromosomal translocations in utero months or years before their promotion into infant acute lymphoblastic B-cell leukemia after secondary postnatal mutations. The results underscore the power of single-cell analyses to characterize the gene expression profiles in a minor population of rare cells, which has broad implications in biomedicine.
authors.affiliation: Laboratory of Immunology and Oncology, Consejo Superior de Investigaciones Cientificas-Alcalá University Research Associated Unit, Madrid, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Sanz
authors.forename: Melchor
authors.initials: M
authors.lastname: Alvarez-Mon
authors.forename: Carlos
authors.initials: C
authors.lastname: Martínez-A
authors.forename: Antonio
authors.initials: A
authors.lastname: de la Hera
mesh_terms: D018941:Antigens, CD19 / Q000032:analysis; D001402:B-Lymphocytes / Q000166:cytology*; D002454:Cell Differentiation; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000032:analysis; D020869:Gene Expression Profiling; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D015260:Neprilysin / Q000032:analysis; D051757:PAX5 Transcription Factor; D017463:Receptors, Complement 3b / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000032:analysis
chemical_list: D018941:Antigens, CD19; D004268:DNA-Binding Proteins; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D017463:Receptors, Complement 3b; D014157:Transcription Factors; D015260:Neprilysin