Functional and kinetic characterization of granulocyte colony-stimulating factor-primed CD34- human stem cells.
We assessed the functional properties and the kinetic status in vitro, and the engraftment potential in vivo of human haematopoietic stem cells according to the expression of CD34 antigen. Lin-CD34- and Lin-CD34+ cells were isolated from granulocyte colony-stimulating factor-primed peripheral blood (PB) cells of healthy donors. The CD34- cell fraction did not contain either clonogenic cells in semisolid culture or long-term culture initiating cells (LTC-IC). However, stroma-dependent liquid cultures and cytokines induced CD34 expression on a minority of stem cells, acquisition of clonogenic capacity and generation of LTC-IC. Significantly higher percentages of quiescent G0 cells and lower percentages of cycling G1 cells were found in Lin-CD34- cells when compared with Lin-CD34+ cells. Kinetic quiescence of Lin-CD34- cells was associated with a significantly higher expression of the negative regulators of the cell cycle, p27Kip1 and p21(cip1/waf1). Cytokine-mediated induction of CD34, in vitro, resulted in cycling of stem cells and downregulation of p27. There was a higher rate of human long-term engraftment in immunocompromised non-obese diabetic (NOD)/recombination activating gene 1null and NOD/severe combined immunodeficient-beta2microglobulin(null) mice injected with CD34+ cells. Thus, our study indicated that CD34 expression on human PB stem cells was associated with haematopoietic activity, cell-cycle recruitment and downregulation of p27Kip1 in vitro and higher engraftment capacity in vivo.
Lemoli
Roberto M
RM
Istituto di Ematologia e Oncologia Medica L. & A. Seràgnoli, University of Bologna, Bologna, Italy. rmlemoli@med.unibo.it
Bertolini
Francesco
F
Petrucci
Maria T
MT
Gregorj
Chiara
C
Ricciardi
Maria R
MR
Fogli
Miram
M
Curti
Antonio
A
Rabascio
Christina
C
Pandolfi
Simona
S
Ferrari
Sergio
S
Foá
Robin
R
Baccarani
Michele
M
Tafuri
Agostino
A
Rabascio
Cristina
C
Fo
Robin
R
D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology*; D002453:Cell Cycle; D002455:Cell Division; D002469:Cell Separation / Q000379:methods; D002478:Cells, Cultured; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006801:Humans; D039041:Integrin alpha4beta1 / Q000032:analysis; D039081:Integrin alpha5beta1 / Q000032:analysis; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D019718:Receptors, CXCR4 / Q000032:analysis; D014183:Transplantation, Heterologous
D018952:Antigens, CD34; D039041:Integrin alpha4beta1; D039081:Integrin alpha5beta1; D019718:Receptors, CXCR4; D016179:Granulocyte Colony-Stimulating Factor