Concentration of human-origin cells as detected by qPCR in injection-site tissues (skin and skeletal muscle) and in the lung of NSG mice at 8 (black bars), 29 (light gray bars) and 92 days (medium gray bars) after intravenous injection of 2 × 106 ABCB5+ MSCs. Shown are means of 10 animals; error bars indicate SD; **P < 0.01, non-paired one-way analysis of variance followed by Tukey’s multiple comparison test. A separate control group (not shown), comprising the mice injected with cell-free vehicle and sacrificed 92 days thereafter, did not reveal any detectable human-origin cells except for muscle tissue of one animal, which was considered an artifact (see Results).