title: A unique population of CD34+ cells in cord blood.
abstract: Human umbilical cord blood (CB) is a rich source of hematopoietic stem cells for both research and stem cell transplantation. In clinical studies, it appears that recovery from myeloablative therapy using CB requires significantly fewer cells than a typical allogeneic marrow transplant. This suggests that CB may be enriched for early hematopoietic progenitors. The present studies were undertaken to determine the presence of CD34+ cells in CB with the phenotypic characteristics of multipotential stem cells. In 22 CB harvests, the average percentage of CD34+ cells was 1.33 +/- 0.21% (SE), a value similar to that in adult normal bone marrows (BM). However, the distribution of CD34+ cells was distinctly different from either BM or granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell harvests. CB contained a defined population of brightly staining CD34+ cells with low side scatter. These CD34 (bright) cells comprised a mean of 14.5 +/- 2.5% of the CB CD34+ cells, whereas < 1% of BM CD34+ cells has been shown to be CD34- bright. Eighty-five to ninety percent were negative for three antigens expressed at an early stage of stem cell maturation: CD38, HLA-DR and LFA-1. Fifty-five percent of these CD34 (bright) cells did not express the CD45RA isoform, an additional marker of immaturity. The antigen-bright cells also lacked lineage-specific antigens including CD33, CD56, CD19, CD10 and CD7 as well as CD71. Approximately 46% were Thy-1+, and 40% expressed c-kit receptors. These data suggest that, by phenotypic criteria, CB may be a particularly enriched source of primitive hematopoietic precursors.
authors.affiliation: Department of Medicine, University of Pittsburgh School of Medicine, Pennsylvania, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Nimgaonkar
authors.forename: R A
authors.initials: RA
authors.lastname: Roscoe
authors.forename: J
authors.initials: J
authors.lastname: Persichetti
authors.forename: W B
authors.initials: WB
authors.lastname: Rybka
authors.forename: A
authors.initials: A
authors.lastname: Winkelstein
authors.forename: E D
authors.initials: ED
authors.lastname: Ball
mesh_terms: D015703:Antigens, CD / Q000032:analysis / Q000097:blood*; D018952:Antigens, CD34; D001854:Bone Marrow Cells; D005260:Female; D005312:Fetal Blood / Q000166:cytology* / Q000276:immunology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology; D006801:Humans; D009077:Mucins / Q000097:blood; D010920:Placenta; D011247:Pregnancy
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D009077:Mucins