title: Ultrastructural features of CD34+ hematopoietic progenitor cells from bone marrow, peripheral blood and umbilical cord blood.
abstract: Hematopoietic progenitor cells from different sources have been widely characterized, but their ultrastructural morphology has never been described in detail. In this study, imunomagnetically separated CD34+ cells from normal bone marrow (BM), mobilized peripheral blood (PBSC) and human umbilical cord blood (CB) were studied by transmission electron microscopy (TEM) using a cytochemical method which reveals endogenous myelo-peroxidase (MPO) activity. This technique is particularly suited for detecting early signs of the myeloid commitment. The CD34+ cells from PBSC were morphologically very homogeneous and 94.7+/-4.5% of these cells were MPO-: these ultrastructural features are generally considered typical of immature cells. The CD34+ BM cells were instead more heterogeneous, with 24.6+/-7.4% showing intense MPO activity. The ultrastructural characteristics of CB cells fell between those observed in PBSC and BM, but there was a high percentage of morphologically immature cells with no evidence of MPO activity (about 83%). The number of apoptotic cells within samples from different sources was also examined both by TEM and flow cytometry. The percentage of apoptotic cells was 0.7% in PBSC, 2.3% in BM, 2.9% in CB from vaginal delivery and 11.6% in CB from cesarean section. These observations confirm the relative phenotypic immaturity of CB in comparison with BM cells; they also suggest that CB collected after cesarean section may be associated with reduced stem cells viability.
authors.affiliation: Centro Trapianti di Midollo, IRCCS Ospedale Maggiore, Università degli Studi di Milano, Milan, Italy. Giorgio.Lambertenghi@unimi.it
authors.forename: G L
authors.initials: GL
authors.lastname: Deliliers
authors.forename: L
authors.initials: L
authors.lastname: Caneva
authors.forename: R
authors.initials: R
authors.lastname: Fumiatti
authors.forename: F
authors.initials: F
authors.lastname: Servida
authors.forename: P
authors.initials: P
authors.lastname: Rebulla
authors.forename: L
authors.initials: L
authors.lastname: Lecchi
authors.forename: E
authors.initials: E
authors.lastname: De Harven
authors.forename: D
authors.initials: D
authors.lastname: Soligo
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis / Q000097:blood*; D017209:Apoptosis; D001773:Blood Cells / Q000166:cytology* / Q000648:ultrastructure; D001854:Bone Marrow Cells / Q000166:cytology* / Q000648:ultrastructure; D002454:Cell Differentiation; D005312:Fetal Blood / Q000166:cytology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000648:ultrastructure*; D006801:Humans; D018189:Immunomagnetic Separation; D008854:Microscopy, Electron; D036103:Nanotechnology; D009195:Peroxidase / Q000032:analysis / Q000378:metabolism; D010641:Phenotype
chemical_list: D018952:Antigens, CD34; D009195:Peroxidase