Hemato-vascular origins of endothelial progenitor cells?

Abstract

Numerous studies have suggested the presence of precursor cells in various tissues and organs with potential to differentiate into endothelial and mural cells, and contribute to blood vessel formation in different physiological and pathological circumstances. Although there is still a lack of consensus in the field regarding the origin, and phenotypic and functional characteristics of putative vascular progenitor cell populations, all agree that further studies are needed to fully explore and exploit their great potential as cell therapy for vascular diseases, as modulators of postnatal blood vessel formation, and as disease biomarkers. Herein, we will review the phenotypic and functional characteristics of endothelial progenitor/precursor cell types thought to be derived from the hematopoietic and vascular systems and contribute to postnatal blood vessel formation, and discuss their potential lineage relationships.

Pro-angiogenic hematopoietic progenitor cells and endothelial colony-forming cells in pathological angiogenesis of bronchial and pulmonary circulation

“…The term EPC has since been used to broadly describe a heterogeneous group of circulating cells that putatively have the capacity to give rise to endothelial cells in vitro or in vivo [5] (Table I). However, conclusive evidence a circulating progenitor cell differentiates into endothelial cells during post-natal life is lacking.…”

“…In most areas, the vasculature is primarily quiescent, with very low rates of replication [1]. However, under the influence of factors such as inflammation, vascular injury, hypoxia, and oxidative stress, vessels respond by mobilizing pro-angiogenic cells to sites of remodeling as well as activating local endothelial cells to proliferate [4,5]. These cells, which originally were termed in the literature as “endothelial progenitor cells” (EPC), are actually myeloid cells and interact with the local endothelial cells in a synergistic way to promote vessel formation.…”

“…These cells, which originally were termed in the literature as “endothelial progenitor cells” (EPC), are actually myeloid cells and interact with the local endothelial cells in a synergistic way to promote vessel formation. EPC are important in vascular homeostasis in both health and disease, including contributing to repairing endothelial injury and neovascularization[4,5]. Because of these critical roles, identifying these progenitor cells and elucidating the mechanisms by which they exert their putative effects has broad implications for understanding and treating human disease.…”

Endothelial Progenitor Cells Physiology and Metabolic Plasticity in Brain Angiogenesis and Blood-Brain Barrier Modeling

“…EPC are involved in vessel development and regeneration, being recruited from the bone-marrow to the peripheral blood, displaying immunopositivity for CD34, CD45, CD133, VEGFR2, c-kit, and, presumably existing as hematopoietic cells with pro-angiogenic activity in vitro and in vivo (Richardson and Yoder, 2011; Yoder, 2012). In adults, there are two origins of EPC: (i) hematopoietic origin (EPC derived from bone marrow multipotent hemangioblasts [VEGFR2(+)VE-cadherin(+)CD45(−) and mesenchymal stem cells (MSC) (CD73(+)CD90(+)CD105(+)CD34(−)CD45(−)]; (ii) and non-hematopoietic origin (EPC found at the sites of extensive angiogenesis but demonstrating no signs of hematopoietic origin, being, probably, derived from tissue multipotent cells) (Chao and Hirschi, 2010; Leeper et al, 2010; Boxall and Jones, 2012). …”

The Implications of Human Stem Cell Differentiation to Endothelial Cell Via Fluid Shear Stress in Cardiovascular Regenerative Medicine: A Review

“…Presently, there is still a lack of formal agreement and consensus in the field regarding the origin, functional, and fundamental characteristics of EPC populations [85], because there is no exclusive EPC marker [86]. In many tissues and organs, the identity of stem cells has remained either elusive or at least equivocal, and some have argued that stem cell markers are akin to spots on a Dalmatian dog; useful for identification, but do no contribute to essential dog (stem cell) functions [87].…”