Intra-arterial infusion of MAPCs results in superior biodistribution. To assess the biodistribution of MAPCs after intra-arterial (IA) delivery, MAPC DLs (10⁶) were infused through the left cardiac ventricle (n = 3) into Rag2/IL-2Rγc^–/– mice. WBI is shown at 4 days (A) and at 30 days (B) after MAPC DL infusion. WBI showed BLI signals distributed throughout the whole body at day 4 (A) and the thoracoabdominal area, face, and paws at day 30 (B), in contrast to mostly thoracic BLI signals after intravenous (IV) delivery (Figure 2B). (C) Tissue homogenates were examined for luciferase activity at day 30 after IV or IA MAPC DL infusion. Lung luminescence after IA infusion was above background but significantly less than lung luminescence after IV delivery (P = .032). After IA delivery, tissue luminescence was significantly higher than in samples of the same tissues after IV delivery in liver (P = .05), kidney (P = .044), and brain (P = .004). These findings show that, when compared with IV delivery, IA infusion results in more diverse homing of MAPC DLs.