[Affiliation between endothelial and intra-embryonic hematopoietic stem cells].
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 precisely determined by detecting the common leukocyte antigen CD45. VEGF-R2 and CD45 are expressed in complementary fashion, namely the hemopoietic clusters in the floor of the aorta are CD45+/VEGF-R2-, while the rest of the aortic endothelium is CD45-/VEGF-R2+. To determine if the hemopoietic clusters are derived from EC, we tagged the E2 endothelial tree with a non-replicative retroviral vector and low density lipoproteins. Twenty four-48 hours later, labelled cells in the vascular tree were found to be either endothelial or hemopoietic but exceptionally both. Another 1-2 days later, groups of labelled cells appear in the dorsal mesentery within the hemopoietic "paraortic foci". Since no CD45+ cells were inserted among endothelial cells at the time of vascular labelling, hemopoietic clusters and foci must be concluded to derive from precursors with an endothelial phenotype.
Jaffredo
T
T
Institut d'Embryologie Cellulaire et Moléculaire du CNRS, Nogent sur Marne. jaffredo@infobiogen.fr
Gautier
R
R
Brajeul
V
V
Dieterlen-Lièvre
F
F
D000818:Animals; D001011:Aorta / Q000196:embryology; D002454:Cell Differentiation; D002642:Chick Embryo; D004730:Endothelium, Vascular / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D005822:Genetic Vectors; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology; D017978:Receptors, Growth Factor / Q000502:physiology; D040262:Receptors, Vascular Endothelial Growth Factor; D012190:Retroviridae
D017978:Receptors, Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D017493:Leukocyte Common Antigens
Filiation entre cellules endothéliales et cellules souches hématopoïétiques intraembryonnaires.