Erythropoietin priming improves the vasculogenic potential of G-CSF mobilized human peripheral blood mononuclear cells

Abstract

From our previous clinical trials, intracoronary infusion of granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (^mobPBMCs) proved to be effective in improving myocardial contractility and reducing infarct volume in acute myocardial infarction. We tested the effect of priming ^mobPBMCs with erythropoietin (EPO) to augment its therapeutic efficacy. ^mobPBMCs were obtained from healthy volunteers after a 3-day subcutaneous injection of G-CSF (10 μg/kg). About 40% of ^mobPBMCs were EPO receptor (EPOR) (+) and responded to 6 h EPO-priming (10 IU/mL) by increasing the expression of vasculogenic factors (i.e. IL8, IL10, bFGF, PDGF, MMP9) and adhesion molecules (i.e. integrin αV, β1, β2, β8) through the JAK2 and Akt pathway. These responses were also observed in PBMCs from elderly patients with coronary disease. The conditioned media from EPO-primed ^mobPBMCs contained various cytokines such as IL8, IL10, TNFα, and PDGF, which enhanced the migration and tube formation capability of endothelial cells. EPO-primed ^mobPBMCs also showed increased adhesion on endothelial cells or fibronectin. Augmented vasculogenic potential of EPO-primed ^mobPBMCs was confirmed in a Matrigel plug assay, ischaemic hindlimb, and myocardial infarction models of athymic nude mice. There were two action mechanisms: (i) cellular effects confirmed by direct incorporation of human ^mobPBSCs into mouse vasculature and (ii) indirect humoral effects confirmed by the therapeutic effect of the supernatant of EPO-primed ^mobPBMCs. Brief ex vivo EPO-priming is a novel method to augment the vasculogenic potential of human ^mobPBMCs, which would help to achieve better results after intracoronary infusion in myocardial infarction patients.