Inhibition of VEGF-induced neoangiogenesisin a Matrigel plug model. (A) In vivo assessment of the vascular targeting capability of ephrinB2-specific scFvs labeled with Alexa 750 in mice bearing VEGF-containing Matrigel plugs. Representative fluorescent images of Matrigel plugs taken from the killed mice at 8 hours after IV injection of Alexa 750–conjugated scFvB11 (top panel), Alexa 750–conjugated scFv2B1 (middle panel), or an irrelevant Alexa 750–conjugated scFv (bottom panel). Color-coded scale of fluorescence counts (× 10³) is shown at right. (B) Quantification of hemoglobin in Matrigel plugs removed from the scFv-treated or untreated mice as indicated, after 10 days after implantation (n = 6). Data are presented as hemoglobin fold change over unstimulated and untreated group (negative control). *P < .001 and **P < .01 versus VEGF-stimulated and untreated positive control. (C) Representative sections of the indicated Matrigel plugs excised on day 10. Endothelial cells were labeled with CD34 (brown), and the sections were counterstained with hematoxylin (blue). Quantification of CD34-positive area is shown in the bottom right panel. Bars represent the mean percentage of positive area ± SD (n = 6). *P < .001 and **P < .01 versus VEGF-stimulated and untreated positive control.