Involvement of vascular endothelial growth factor, angiopoietin and their receptors in the process of human embryonic haematogenesis / 中国组织工程研究

ABSTRACT

BACKGROUND: Vascular endothelial growth factor family and its receptor play an important role in the process of angiogenesis and neovascularization. Recently, the effect of vascular endothelial growth factor family on blood has been paid much attention. OBJECTIVE: To observe the expression of vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor C (VEGFC) and their receptors as well as angiopoietin-1 (ang-1),angiopoietin-2(ang-2) and their receptors in the blood island of yolk sac and aorta-gonadalmesonephros (AGM) region at embryonic 3 to 12 weeks, so as to investigate the effect of VEGF and angiopoietin family in the process of haematogenesis. DESIGN: Single sample observation. SETTING: Weifang Medical College, Experimental Center of Morphology and Staff Room of Anatomy. MATERIALS This experiment was carried out at Weifang Medical College from February 2002 to August 2004. Specimens were collected from 47 pregnant women's 3-to-12-week abortive embryos. Informed consent was obtained from the pregnant women. METHODS: Specimens were performed successive sections. Two sections were drawn out every other 10 sections. Hematoxylin-eosin staining and immunohistochemical staining were performed. Polyclonal anti-vascular endothelial growth factor C, fms like protein tyrosine kinase(PTK), flt-4,ang-1, ang-2,Tie-2 antibody, monoclonal anti-vascular endothelial growth factor A and fetal liver kinase 1 (flk1) antibody were used for incubation overnight at 4 ℃ .Goat anti-mouse IgG and SABC solution were used separately for 2 hours. 3,3'2 diaminoazobenzidine (DAB) was used to develop. Serum of normal rabbit or mouse were used separately to replace primary antibody as negative control. They were observed and taken photographs under optical microscope. MAIN OUTCOME MEASURES: ①Blank expression of VEGFA and VEGFC and their receptors in the blood island of yolk sac and AGM region at embryonic 3 to 12 weeks. ②Blank expression of ang-1 and ang-2 and their receptors in the blood island of yolk sac and AGM region at embryonic 3 to 12 weeks. RESULTS: ①On the 21st to 25th day , vascular endothelial cells and hematopoietic cells in blood island of yolk sac strongly expressed VEGFA and its receptor fms like PTK and flk1, VEGFC and its receptor flk4, ang2 and its receptor Tie-2 protein, weakly expressed ang-1 protein. ②From the fourth week of development, dorsal aorta and mesonephros expressed above-mentioned various factors and their receptors . Immune positive reactants gathered in the large and round hematopoietic cells with nucleus. The cell quantity reached the peak at week 7. After week 8, the number of positive cells was significantly decreased, and almost all the blood cells were immune negative reaction at week 12. ③Gonad mainly expressed VEGFA , fms like PTK, flt-4,ang-1 ,ang-2 and Tie-2 protein at weeks 6 to 8 , but did not express VEGFC and flkl. ④ The expression of above-mentioned factors were not detected in the vascular endothelial cells in AGM region. CONCLUSION: Hematopoietic cells and endothelial cells of blood island of yolk sac of human embryo as well as dorsal aorta and mesonephros coexpresses various factors related to angiogenesis and haematogenesis. Haematogenesis of human embryos occurs at the fourth week.