In vitro cell cycle dynamics of primitive hematopoietic cells from human umbilical cord blood.
The goal of the present study was to investigate the specific way in which recombinant stimulatory cytokines modulate the cell cycle dynamics of primitive hematopoietic cells in vitro. A human cord blood-derived cell population, enriched for CD34(+) Lin(-) cells, was obtained by negative selection and cultured in liquid cultures, in the absence or presence of recombinant stimulatory cytokines. The proportion of cells in each phase of the cell cycle, as well as the expression of cyclin D3, cyclin-dependent kinase-4 (cdk4), p16, p21 and p27, was determined at different time points. At the onset of culture, the vast majority of the cells were in the G(0)/G(1) phase of the cell cycle. In the absence of cytokines, most cells remained in such a phase and no cell cycle activity was detected throughout the culture period, which correlated with the absence of population doublings. In the presence of cytokines, approximately four cell cycles, with a proportionate population doubling, were observed within the first 4 days of culture. In cultures incorporating cytokines, expression levels of cyclin D3 and cdk4 were higher than in their absence; in contrast, the levels of the cell cycle inhibitors p16 and p21 were higher in cultures without cytokines. Levels of p27 were also higher in the presence of cytokines. Our results indicate that the proliferation of primitive hematopoietic cells in liquid culture is promoted by recombinant cytokines via the induction of specific positive regulators of the cell cycle and down-regulation of particular cell cycle inhibitors.
Oncology Hospital, National Medical Center, IMSS, Mexico City, Mexico.
Antonio
A
Alvarado-Moreno
Antonieta
A
Chávez-González
Arturo
A
Cérbulo
Lourdes
L
Arriaga
Hector
H
Mayani
D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D016895:Culture Media, Serum-Free; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000096:biosynthesis / Q000235:genetics; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis / Q000235:genetics; D016207:Cytokines / Q000494:pharmacology*; D005312:Fetal Blood / Q000166:cytology*; D005786:Gene Expression Regulation / Q000187:drug effects; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D011994:Recombinant Proteins / Q000494:pharmacology
D018797:Cell Cycle Proteins; D016895:Culture Media, Serum-Free; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016207:Cytokines; D016298:Hematopoietic Cell Growth Factors; D011994:Recombinant Proteins; D018844:Cyclin-Dependent Kinases