Hemangioblasts, angioblasts, and adult endothelial cell progenitors

Abstract

After decades of speculation, proof of embryonic hemangioblasts finally emerged a few years ago. Surprisingly, at about the same time, evidence for adult hemangioblasts began to appear, and recent single-cell bone marrow transplants have confirmed their existence. Embryonic and adult hemangioblasts appear to share antigenic determinants, including CD34, ACC133, and VEGFR2, although their phenotype may be plastic. They also respond to similar factors, prominent among them vascular endothelial growth factor (VEGF). In the adult, hemangioblasts reside principally in the bone marrow, although they may subsequently leave that niche to reside in nonhematopoietic tissues. A number of studies indicate that these cells or their progeny may be a significant source of endothelial cells in adult pathologic and nonpathologic vascularization, and may participate in vascular repair. In addition to hemangioblasts, a more differentiated source of endothelial cell progenitors may be present in the blood, namely, monocytes or monocytic-like cells. The relative importance of the two cell types in vivo is not clear, though endothelial cells derived from the two sources may not be identical, and hemangioblasts seem to provide a stimulus for differentiation of the monocytes. Treatment with exogenous bone marrow-derived cells can promote neovascularization, accelerate restoration of blood flow to ischemic tissues, and improve cardiac function after infarct. Hence, there is great hope that either alone, in combination with angiogenic factors, or as gene therapy vectors, we can harness these cells to treat ischemic and vascular diseases in the relatively near future. Anat Rec Part A 276A: 13-21, 2004.

Carbon Monoxide and Nitric Oxide Mediate Cytoskeletal Reorganization in Microvascular Cells via Vasodilator-Stimulated Phosphoprotein Phosphorylation

“…We also directly compare the CO effects to those of NO in EPCs, platelets, and microvascular endothelial cells. Our studies demonstrate that both vasoactive gases promote cytoskeletal changes through site-and cell type-specific VASP phosphorylation; however, these responses to NO and CO are blunted in diabetes and may be responsible for reduced vascular repair and tissue perfusion (24,25).…”

Presence of endothelial progenitor cells, distinct from mature endothelial cells, within human CD146+ blood cells

“…The expression of hematopoietic markeroncirculating CD146 + progenitors is consistent with the close association of hematopoietic and endothelial lineages during ontogeny. The existenceo fac ommon precursor, calledhemangioblast, hasbeen demonstrated in adults (37)(38)(39). These hemangioblasts share the same markers with the hematopoietic stemcells i.e.CD133,CD34, VEGFR2 (KDR), CD117 and CD45 (38).…”

“…The existenceo fac ommon precursor, calledhemangioblast, hasbeen demonstrated in adults (37)(38)(39). These hemangioblasts share the same markers with the hematopoietic stemcells i.e.CD133,CD34, VEGFR2 (KDR), CD117 and CD45 (38). Remarkably,as imilarp henotype is also displayedbythe circulating CD34 + cells thatgiverise to late EPCs (34,3 6) and by the subpopulation of blood CD146 + late EPCs identifiedinthis study.These data arecompatible with apossible expression of CD146 on hemangioblasts, an hypothesis also supported by the presence of CD146o nh ematopoietic neoplastic cells (40).…”

Obese Diabetic Mouse Environment Differentially Affects Primitive and Monocytic Endothelial Cell Progenitors

“…Studying putative EC progenitor dysfunction in diabetes is not simple, because the antigenic phenotype of bone marrow-derived cells capable of differentiating into ECs remains poorly defined, probably because it is plastic [14]. Nevertheless, studies on various subsets of blood and BMCs have provided ample evidence that there are at least two distinct classes of bone marrow-derived EC progenitors, primitive progenitors and monocytic-like progenitors.…”