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The expression of basic fibroblast growth factor 1 during human embryonic yolk sac hematopoiesis
Pages: 535-539
Year: Issue:  8

Keyword:  Yolk sacTranscription factorHematopoietic stem cellFGF1Human embryo;
Abstract: Objective To explore the effect of basic fibroblast growth factor 1(bFGF1)during embryonic development on hematopoiesis,to study the expression of FGF1,vascular endothelial growth factor receptor(KDR),CD133,CD34 and transcription factors Ihh,SCL,GATA-1,GATA-2 and PU.1 in the yolk sac,and to learn about the role and relationships of FGF1,hematpoietic cells and transcription factors during embryonic hematopoiesis.Methods 10 μm sections and total RNA were prepared from 107 human embryos aged 3-12 weeks.Immunohischemical SP staining and RT-PCR were performed.Results The yolk sac blood islands of human 3~12 weeks embryos consisted of peripheral vascular endothelial cells and central hematopoietic cells.The expression of FGF1 was firstly found in visceral mesoderm around periphery of yolk sac blood island at day 16,while was little iaside KKDR was not or lowly expressed and CD34 and CD133 were not expressed then.The expression increased,gray value decreased and staining enhanced at day 21.Strong staining of CD34+,CD133+ and KDR+ cells were found in blood island and mesoderm at day 30,their gray values changed from 156±16.173±18 and 160±14 to 53±7.52±6 and 69±8 respectively.FGF1 expression was strong positive,the gray valne declined dramatically from 161±13 to 40±5.Some positive cels formed vessel-like structure along the periphery of blood island.Moderate expression of CD34+、CD133+、KDR+ cells increased at day 45,the cells aggregated into mass in blood island and FGF1+ cells did the same in blood island,while little in mesoderm.Its gray valvc was increased.After 7 weeks.CD133+,KDR+,CD34+ cells significantly decreased their gray values inereased,the staining became week.FGF1 was weakly expressed in yolk sac and its gray value inereased to 179±22.RT-PCR showed Ihh,SCL,GATA-1 and GATA-2 were expressed at different time in yolk sac.PU.1 were not expressed at day 16,and then expressed.Conclusions The hematopoietic properties of yolk sac may be dependent on signaling through FGF receptors and FGF1 plays an important role in hematopoietic stem cell homeostasis.The FGF pathway regulates primitive hematopoiesis by modulating transcription factors such as Gatal expression level and activity.
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