Table 1.

Properties of endothelial progenitor cells and vascular stem cells

Cell type		Origin	Isolation/expansion	Colony formation and type	In vitro properties				In vivo properties			Surface phenotype
					AcLDL uptake	Lectin binding	eNOS vWf	Tube formation	In vivo homing ischemic sites	Vasculogenesis	Paracrine effect
Historical EPCs [Ref. 28]		Blood	PB-MNCs enriched for CD34→plating→expansion of adherent cells	At 7 days, clusters of round cells surrounded by spindle-shaped cells expressing EC markers	+	Not tested	+	+	+	+	Not tested	CD34+ VEGFR2+ CD45+/− CD31+
Early outgrowth	CFU-Hill	Blood	Preplating of PB-MNCs→selective replating and expansion of non-adherent cells	At 5 days, colonies characterized by elongated sprouting cells radiating from a central cluster and expressing EC markers	+	+	+/−	+	+	−	+	CD34+/− CD133+ VEGFR2+ CD45+/− CD14+/− CD115+ CD31+
	CACs	Blood	Plating of PB-MNCs→at 4 days, removal of non-adherent cells→characterization of adherent cells	At 4 days, adherent cells express EC markers but do not form colonies	+	+	+/−	+	+	−	+	CD34+/− CD133+ VEGFR2+ CD45+/− CD14+/− CD115+ CD31+
Late outgrowth		Blood Umbilical cord Vessel wall Bone marrow	Plating of PB-MNCs→removal of non-adherent cells→at 7–21 days, colony formation	At 7–21 days, colonies of highly proliferative ECs	+	+	+	+	+	+	+/−	CD34+ CD133− VEGFR2+ CD45− CD14− CD115− CD31+
VSCs		Heart	Enzymatic digestion of cardiac tissue→sorting for c-kit and KDR→expansion in vitro	At 2–3 weeks, multicellular clones derive from single cells	Not tested	Not tested	+ (after differentiation)	Not tested	+	+	−	c-kit+ CD34− CD133− VEGFR2+ CD45− CD14− CD115− CD31−

EPCs endothelial progenitor cells, CFU colony-forming unit, CACs circulating angiogenic cells, ECFCs endothelial colony-forming cells, PB-MNCs peripheral blood mononuclear cells, EC endothelial cell, AcLDL acetylated low-density lipoprotein, eNOS endothelial nitric oxide synthase, vWf von Willebrand factor, VSCs vascular stem cells