title: Intra-aortic clusters undergo endothelial to hematopoietic phenotypic transition during early embryogenesis.
abstract: Intra-aortic clusters (IACs) attach to floor of large arteries and are considered to have recently acquired hematopoietic stem cell (HSC)-potential in vertebrate early mid-gestation embryos. The formation and function of IACs is poorly understood. To address this issue, IACs were characterized by immunohistochemistry and flow cytometry in mouse embryos. Immunohistochemical analysis revealed that IACs simultaneously express the surface antigens CD31, CD34 and c-Kit. As embryos developed from 9.5 to 10.5 dpc, IACs up-regulate the hematopoietic markers CD41 and CD45 while down-regulating the endothelial surface antigen VE-cadherin/CD144, suggesting that IACs lose endothelial phenotype after 9.5 dpc. Analysis of the hematopoietic potential of IACs revealed a significant change in macrophage CFC activity from 9.5 to 10.5 dpc. To further characterize IACs, we isolated IACs based on CD45 expression. Correspondingly, the expression of hematopoietic transcription factors in the CD45(neg) fraction of IACs was significantly up-regulated. These results suggest that the transition from endothelial to hematopoietic phenotype of IACs occurs after 9.5 dpc.
authors.affiliation: Department of Hematopoietic Stem Cells, SSP Stem Cell Unit, Kyushu University Faculty of Medical Sciences, Fukuoka, Japan.
authors.forename: Chiyo
authors.initials: C
authors.lastname: Mizuochi
authors.forename: Stuart T
authors.initials: ST
authors.lastname: Fraser
authors.forename: Katia
authors.initials: K
authors.lastname: Biasch
authors.forename: Yuka
authors.initials: Y
authors.lastname: Horio
authors.forename: Yoshikane
authors.initials: Y
authors.lastname: Kikushige
authors.forename: Kenzaburo
authors.initials: K
authors.lastname: Tani
authors.forename: Koichi
authors.initials: K
authors.lastname: Akashi
authors.forename: Manuela
authors.initials: M
authors.lastname: Tavian
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sugiyama
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D001011:Aorta / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D054337:Cell Dedifferentiation; D004622:Embryo, Mammalian; D047108:Embryonic Development; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D051379:Mice
chemical_list: D015703:Antigens, CD; D015415:Biomarkers