Vascular Endothelium - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 468

Tabl e 9. 4. Identification markers of endothelial progenitor (EPC) and circulating endothelial cells
(CEC; Source: [ 844 ]; MCAM: melanoma cell adhesion molecule [a.k.a. cell-surface glycoprotein
MUC18 and CD146]; PTPRc: protein Tyr phosphatase, receptor type C [a.k.a. CD45]; SCA1:
stem cell antigen-1 [a.k.a. lymphocyte antigen-6A]; SCFR: stem cell factor receptor; vWF: von
Willenbrand factor). CD14 is a pattern-recognition receptor. CD133 is the prototypic member
of pentaspan transmembrane glycoproteins. CD45 dim is a marker of endothelial progenitor cells.
During maturation, the CD45 hematopoietic marker disappears to be replaced by endothelial labels.

Marker EPC CEC

Stem cell markers
CD34 2 + ±

CD133 2 + −

SCFR + −

Ataxin-1 + −

Endothelial markers
VEGFR2 2 + +

+ +

PECAM1 2

vWF + 2 +

+ /− +

MCAM 2

NOS3 + +

Leukocyte markers
PTPRc dim/- −

CD14 + /− −

and myeloid progenitor cells; 19 vascular stem cells are precursors of endothelial
progenitors and, secondarily, endothelial cells and pericytes.
Hemangioblasts are mobilized by several factors mainly via activated endothelial
nitric oxide synthase and matrix metallopeptidase MMP9 produced in bone-marrow
niches [ 870 ]. Nitric oxide availability rises on signaling by growth hormone and
insulin-like growth factor-1. On the other hand, NO inhibitors (e.g., asymmetric
dimethylarginine [ADMA]) prevent mobilization and differentiation of endothe-
lial progenitor cells, their incorporation into endothelial tube-like structures, and
formation of colony-forming units from cultured peripheral blood mononuclear
cells [ 870 ]. Estrogens mobilize endothelial progenitors via estrogen receptor ER

α

and ER (a.k.a. nuclear receptors NR3a1 and NR3a2), MMP9, and NOS3 [ 870 ].

Smoking increases oxidative stress and reduces NO availability.
Hemogenic endothelial cells that line blood vessels in the embryo give rise to
progenitors of blood cells in fetal liver and adult bone marrow. Hematopoietic
progenitor cells can actually form clusters attached to the endothelium of the ventral
wall of the abdominal aorta during embryogenesis.

β

19 Lymphoid progenitor cells differentiate into B, T, and NK lymphocytes; myeloid progenitor cells
into granulocytes, monocytes, erythrocytes, thrombocytes, and dendritic cells.