Intraaortic hemopoietic cells are derived from endothelial cells during ontogeny.
We have investigated the developmental relationship of the hemopoietic and endothelial lineages in the floor of the chicken aorta, a site of hemopoietic progenitor emergence in the embryo proper. We show that, prior to the onset of hemopoiesis, the aortic endothelium uniformly expresses the endothelium-specific membrane receptor VEGF-R2. The onset of hemopoiesis can be determined by detecting the common leukocyte antigen CD45. VEGF-R2 and CD45 are expressed in complementary fashion, namely the hemopoietic cluster-bearing floor of the aorta is CD45(+)/VEGF-R2(-), while the rest of the aortic endothelium is CD45(-)/VEGF-R2(+). To determine if the hemopoietic clusters are derived from endothelial cells, we tagged the E2 endothelial tree from the inside with low-density lipoproteins (LDL) coupled to DiI. 24 hours later, hemopoietic clusters were labelled by LDL. Since no CD45(+) cells were inserted among endothelial cells at the time of vascular labelling, hemopoietic clusters must be concluded to derive from precursors with an endothelial phenotype.
Jaffredo
T
T
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France; 49 bis, Avenue de la Belle Gabrielle, France. jaffredo@infobiogen.fr
Gautier
R
R
Eichmann
A
A
Dieterlen-Lièvre
F
F
D000818:Animals; D001011:Aorta / Q000196:embryology* / Q000648:ultrastructure; D019070:Cell Lineage; D002642:Chick Embryo; D003370:Coturnix / Q000196:embryology; D004730:Endothelium, Vascular / Q000196:embryology* / Q000648:ultrastructure; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D017493:Leukocyte Common Antigens / Q000302:isolation & purification; D008077:Lipoproteins, LDL / Q000302:isolation & purification; D008954:Models, Biological; D020794:Receptor Protein-Tyrosine Kinases / Q000302:isolation & purification; D017978:Receptors, Growth Factor / Q000302:isolation & purification; D040262:Receptors, Vascular Endothelial Growth Factor
D008077:Lipoproteins, LDL; D017978:Receptors, Growth Factor; C032629:acetyl-LDL; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D017493:Leukocyte Common Antigens