hMSCs promote angiogenesis in an in vivo sponge model. NMRI nude mice bearing a subcutaneous cellulose sponge treated with PBS (negative control) or FGF-2 (200 ng; positive control) or hMSCs (104 cells) under the dorsal skin. (A) Representative three-dimensional fluorescence images of mice after IV injection of 50 μM Alexa700-labeled RAFT-c(−RGDfK-)4. (B) Box plot of fluorescence intensity, recorded as photons per pixel for a specified region of interest (ROI). The data are expressed as the mean ± SD (n = 3 to 6). (C) Animals were euthanised on day 7, and the sponges were photographed. (D) The amount of haemoglobin (Hb) was higher in the FGF-2- and hMSC-treated groups than in the PBS-treated group. The data are expressed as the mean ± SD of two experiments (12 mice in each group; **P <0.0007). hMSC, human mesenchymal stem cell; IV, intravenous; PBS, phosphate-buffered saline; SC, subcutaneous; SD, standard deviation.