Figure 3

Angiogenic response in the CAM after implantation of HEK cell aggregates in control (water-injected) or glucose-treated embryos. HEK (A,B,C) and HEK-VEGF (D,E,F) cells induce nodule formation in both control and hyperglycemic embryos. However, note that in HEK-VEGF-nodules, although nodules were of the same size in both conditions (D = control; E = glucose) and vessels penetrated the nodule in both of them, VEGF secreted by the nodule did not correct hyperglycemia-induced vascular defects in the adjacent CAM. Upper and lower quarters of the image in (E) show obvious vascular defects in the vicinity of the nodule compared with (D). N = nodule, PN = perinodular area, and arrows show vessels penetrating in the nodule. In addition, in HEK-VEGF-nodules, the newly formed vessels are tortuous and morphologically distinct from vessels found in HEK-nodules vascu-larization. PTK787/ZK222584 (0.1 µg/µL), a VEGF receptor inhibitor, applied close to the HEK-VEGF cell aggregates, 2 d after grafting, inhibited vascularization of the nodule (F), but did not inhibit vascularization of HEK nodule (C). In detail (E), representation of an extreme case showing a strong local proangiogenic response around the HEK-VEGF nodule and decreased angiogenesis in the perinodular area in the hyperglycemic CAM.