Blood-borne seeding by hematopoietic and endothelial precursors from the allantois

Abstract

Until now the allantois has not been considered as a hematopoietic organ. Here we report experimental evidence demonstrating the in situ emergence of both hematopoietic and endothelial precursors in the avian allantoic bud. When the prevascularized allantoic bud from a quail embryo was grafted in the coelom of a chicken host, hematopoietic and endothelial cells later were found in the bone marrow of the host. Because the graft was located at a distance from the limb bud, these cells could reach the bone marrow only by the circulatory pathway. This blood-borne seeding may be accomplished by distinct hematopoietic and endothelial precursors, or by hemangioblasts, the postulated common precursors of these two lineages; we consider the latter interpretation more likely. We also show by reverse transcription-PCR that the allantois region expresses very early the GATA genes involved in hematopoiesis and some ␤-globin chain genes.

Definitive erythropoiesis in chicken yolk sac

“…It has been well-documented that extraembryonic tissues, including the yolk sac and allantois in birds and mammals and the placenta in mammals, contribute to the generation of definitive erythrocytes during amniote development (Dantschakoff, 1908;Moore and Owen, 1965;Moore and Metcalf, 1970;Dieterlen-Lievre et al, 1976;Weissman et al, 1978;Beaupain et al, 1979;Caprioli et al, 1998;Palis and Yoder, 2001;McGrath and Palis, 2005;Mikkola et al, 2005;Ottersbach and Dzierzak, 2005;Zeigler et al, 2006;Corbel et al, 2007;Samokhvalov et al, 2007;Lux et al, 2008;Rhodes et al, 2008). What remain not well-understood are the precise cellular source and niche of definitive erythropoiesis and the relative contributions of intraembryonic-and extraembryonic-generated definitive erythrocytes in embryonic blood.…”

The Id proteins and angiogenesis

“…Two possible sources of endothelialization are: (1) Endothelial migration (Bergers et al, 1999;Hanahan and Folkman, 1996) from adjacent preexisting blood vessels and (2) recruitment of bone marrow-derived endothelial precursor cells (CEPs) from the peripheral circulation. CEPs can be considered embryonic angioblasts that migrate, proliferate and have the capacity to di erentiate into mature endothelial cells (Caprioli et al, 1998;Co n et al, 1991;Robert et al, 1996).…”

Genetically modified CD34+ cells as cellular vehicles for gene delivery into areas of angiogenesis in a rhesus model

“…16 In addition to these studies based on animal models of transplantation of CD34 + cells, a variety of other experimental observations support the intimate role of CD34 + cells in angiogenesis, including studies on implanted vascular grafts [18][19][20][21][22][23][24] and molecularly based histological 25 and embryological studies. [26][27][28][29][30][31][32][33][34][35][36] Several threads of evidence converge therefore to strongly support the existence in the adult of circulating progenitor cells with endothelial potential. 17 Transduction of human and non-human primate CD34…”