A Novel and Simplified Method of Culture of Human Blood-Derived Early Endothelial Progenitor Cells for the Treatment of Ischemic Vascular Disease

Endothelial progenitor cells (EPCs) consist of two different subpopulations named early (eEPCs) and late EPCs (IEPCs) that are derived from CD14(+) and CD14(-) circulating cells, respectively. These cells are regularly cultured over fibronectin-coated surfaces in endothelial basal medium (EBM)-2 supplemented with insulin-like growth factor (IGF-1), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and fibroblast growth factor (FGF). We have developed a new and simplified method for culturing human EPCs obtained from peripheral blood and tested their ability to preserve cardiac function following infarction. We first demonstrated that eEPCs derived from human peripheral blood mononuclear cells (PBMCs) and cultured in EBM-2 medium supplemented with autologous serum (10%) over fibronectin-coated surfaces (10 mu g/ml) in the presence of IGF-1 (50 ng/ml) only, have a secretome similar to eEPCs cultured under regular conditions with IGF-1, VEGF, EGF, and FGF. Our data also indicate that IGF-1 modulates PBMC secretome in a dose-dependent manner. In another series of experiments, we showed that PBMCs cultured in suspension in bags (S-PBMCs) in basal medium supplemented with fibronectin and IGF-1 secrete significant amounts of stem cell factor (SCF, 31.3 +/- 3.1 pg/ml)), hepatocyte growth factor (HGF, 438.6 +/- 41.4 pg/ml), soluble tumor necrosis factor receptor 1 (sTNFR1, 127.1 +/- 9.9 pg/ml), VEGF (139.3 +/- 9.6 pg/ml), and IGF-1 (147.2 +/- 46.1 pg/ml) but very low levels of TNF-alpha (13.4 +/- 2.5 pg/ml). S-PBMCs injected intravenously into NOD SCID mice migrated to the injured myocardium, reduced cardiac fibrosis, enhanced angiogenesis, and preserved cardiac function after myocardial infarction (MI) in a manner similar to eEPCs cultured under standard conditions. In conclusion, we show in this study a refined and optimized method for culturing eEPCs. Our data indicate that S-PBMCs are composed of several cell populations including eEPCs and that they secrete high amounts of antiapoptotic, anti-inflammatory, and proangiogenic factors capable of preserving cardiac function following MI.