ABSTRACT
To establish a basis for deep investigation of the role of microRNA (miRNA) in the regulation of hematopoiesis, differential expression profiles of miRNA between human cord blood CD34(+)CD38(-) and CD34(+)CD38(+) cells were analyzed. Mononuclear cells from cord blood (CB) of healthy donors were separated by Ficoll-Hypaque density gradients. CD34(+)CD38(-) and CD34(+)CD38(+) cells were sorted by using FACS Vantage SE. Their mRNA were then extracted and hybridized to miRNA microarray chip. The resulting data were analyzed with GeneSpring and informatics technique. The results showed that eleven miRNAs were found to be downregulated and 73 miRNAs to be upregulated by at least two-fold in the CD34(+)CD38(+) cells of CB, compared with the CD34(+)CD38(-) cells, which maintained CD34(+)CD38(-) cells' self-renewal and multiple lineage potential, that were defined as "stemness" miRNAs. 12 of the 84 genes (14.29%) were common to 33 hematopoietic-expressed miRNAs expressed by CD34(+) cells from both peripheral blood and bone marrow in Georgantas's study, which included 10 upregulated miRNAs (hsa-miR-23b, -26b, -92, -107, -130a, -181a, -197, -213, -222, -223) and 2 downregulated ones (hsa-miR-16a, -155). Some "stemness" miRNAs undergo CD34 antigen-like expression pattern during development and commmitted differeniation of hematopoietic stem cell/progenitors. Hematopoiesis-associated miRNA clusters and putative target genes could be found with informatics technique. It is concluded that the hematopoietic "stemness" miRNAs play important roles in normal hematopoiesis: miRNA expression profiles of hematopoietic stem cell/progenitors --> their gene expression profiles --> their self-renewal and lineage-commmitted differeniation.