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Expression of genes regulating angiogenesis in human circulating hematopoietic cord blood CD34+/CD133+ cells

Authors


Pomyje Jiří Department of Pathophysiology, 1st Medical Faculty, Charles University Prague, U nemocnice 5, Praha 2, 128 53, Czech Republic Tel: +420 2 2496 5901, +420 2 2496 5926 Fax: +420 2 2491 2834 e-mail: jpomy@lf1.cuni.cz

Abstract:

Objectives: Human CD34+ cells represent a heterogeneous population of immature cells which may differentiate to various cell types. The aim of the study was to determine angiogenesis regulating genes expression in CD34+ cells, their subpopulations, and during their differentiation induced by hematopoietic growth factors.

Material and methods: We have measured the expression of angiogenesis regulating genes angiopoietin-1 (Ang-1), angiopoietin-1 (Ang-2) and their receptor Tie-2, vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and VEGFR-2 in sorted population of CD34+ and CD34+/CD133+ cells from human cord blood and bone marrow, and in their differentiating progeny, using real time reverse transcriptase polymerase chain reaction. The hematopoietic differentiation of CD34+ cells was induced in semisolid or liquid differentiation supporting media containing appropriate hematopoietic growth factors.

Results: A higher expression of Ang-1, Ang-2, and Tie-2 mRNAs was detected in CD34+/CD133+ cord blood cells as compared with CD34−/CD133− fraction, but no expression of these genes was detected in burst-forming unit erythroid (BFU-E) nor colony-forming unit granulocyte macrophage (CFU-GM) colonies. The level of Ang-1 and Tie-2 mRNAs, but not that of Ang-2 mRNA gradually decreased during a 14-d incubation of cord blood CD34+ cells in a liquid culture. A significantly higher expression of VEGF mRNA was in BFU-E as compared with CFU-GM cell colonies and CD34+/CD133+ cells. VEGFR-1 mRNA was equally expressed in CD34+/CD133+ and CD34−/CD133− cells as well as in BFU-E and CFU-GM colonies. Expression of VEGFR-2 mRNA was detected at the borderline of method sensitivity only in CD34+/CD133+ cells.

Conclusion: CD34+/CD133+ cord blood cells express Ang-1, Ang-2 and VEGF as well as their receptor mRNAs, suggesting a role of these cells in regulation both angiopoiesis and hematopoiesis.

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