title: Clonal heterogeneity in growth kinetics of CD34+CD38- human cord blood cells in vitro is correlated with gene expression pattern and telomere length.
abstract: Human hematopoietic stem cells (HSCs) are characterized by an extensive proliferative capacity that decreases from fetal liver to cord blood (CB) to adult bone marrow. In previous studies, it was demonstrated that the proliferative capacity of individual CD34+CD38- HSC clones is correlated with their growth kinetics in vitro and that HSC turnover in vivo can be estimated by telomere-length measurements. The present study was aimed at the characterization of the clonal composition of CD34+CD38- human umbilical CB cells in terms of growth kinetics, telomere length, and gene expression profile. For this purpose, individual CD34+CD38- CB cells were sorted into 96-well plates containing serum-free medium supplemented with six growth factors. During expansion, cell numbers in each individual well were scored in 3-day intervals. Once sufficient cell numbers were achieved, telomere length was measured by flow fluorescence in situ hybridization (flow FISH). In a second set of experiments, gene expression and colony-forming capacity were analyzed in slowly growing clones as compared with fast-growing clones, using linear amplification and oligonucleotide microarrays (HG-U133A; Affymetrix). Individual CD34+CD38- cells from CB displayed an extensive functional heterogeneity in growth kinetics. Among highly proliferative clones, the most slowly growing clones were characterized by the longest telomeres. Furthermore, significant differences in gene expression were detected between slow- and fast-growing clones, whereas no significant difference in colony-forming capacity was observed. These data provide further evidence for a functional hierarchy in the human HSC compartment and suggest a link between telomere length and proliferation capacity of individual HSC clones.
authors.affiliation: Department of Oncology and Hematology, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Kerol
authors.initials: K
authors.lastname: Bartolović
authors.forename: Stefan
authors.initials: S
authors.lastname: Balabanov
authors.forename: Birgit
authors.initials: B
authors.lastname: Berner
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Bühring
authors.forename: Martina
authors.initials: M
authors.lastname: Komor
authors.forename: Sven
authors.initials: S
authors.lastname: Becker
authors.forename: Dieter
authors.initials: D
authors.lastname: Hoelzer
authors.forename: Lothar
authors.initials: L
authors.lastname: Kanz
authors.forename: Wolf-Karsten
authors.initials: WK
authors.lastname: Hofmann
authors.forename: Tim H
authors.initials: TH
authors.lastname: Brümmendorf
mesh_terms: D036541:ADP-ribosyl Cyclase / Q000096:biosynthesis*; D051997:ADP-ribosyl Cyclase 1; D015703:Antigens, CD / Q000096:biosynthesis*; D018952:Antigens, CD34 / Q000096:biosynthesis*; D049109:Cell Proliferation; D002469:Cell Separation / Q000379:methods*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005312:Fetal Blood / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D066298:In Vitro Techniques; D007700:Kinetics; D008027:Light; D008562:Membrane Glycoproteins; D008747:Methylcellulose / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D012189:Retrospective Studies; D012542:Scattering, Radiation; D019089:Stem Cell Factor / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism; D016615:Telomere / Q000648:ultrastructure*; D013997:Time Factors
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D016895:Culture Media, Serum-Free; D008562:Membrane Glycoproteins; D019089:Stem Cell Factor; D008747:Methylcellulose; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1