Experimental design. Three somatic cell lines were reprogrammed to pluripotent state (human induced pluripotent stem cells; hiPSCs) and differentiated into hiPSC-derived endothelial cells (hiPSC-ECs). Somatic cells and hiPSC-ECs were labeled with uncoated superparamagnetic iron-oxide nanoparticles (uSPIONs) and compared. Abbreviations: HUVECs, human umbilical vein endothelial cells; HSVECs, human saphenous vein endothelial cells; hDFs, adult human dermal fibroblasts; hiPSCs-HU, induced pluripotent stem cells derived from HUVECs; hiPSCs-HS, induced pluripotent stem cells derived from HSVECs; hiPSCs-HF, induced pluripotent stem cells derived from hDFs; ECs-HU, endothelial cells differentiated from hiPSCs-HU; ECs-HS, endothelial cells differentiated from hiPSCs-HS; ECs-HF, endothelial cells differentiated from hiPSCs-HF.