Figure 5. The effect of cell type specific upregulation of R-Ras on vessel maturation and functions.

(A–E) The effect of endothelial specific R-Ras. A timetable of Matrigel implantation in Tie2-rtTA transgenic mice, lentivirus infection, R-Ras38V induction by doxycycline (Dox), and lectin i.v. perfusion is shown (A). Vessel density in the Matrigel plugs at Day 11 (B). Relative perfusion efficiency of i.v. injected lectin at Day 11 (C). (D and E) Matrigel sections were stained for NG2 and CD31 (D), and pericyte coverage of the vessels was determined by image analysis (E). (F) VEGF-induced Matrigel angiogenesis produces extensively ‘bloody’ plugs in R-Ras KO mice demonstrating enhanced leakiness of pathologically regenerating vessels in the absence of R-Ras. (G and H) The effect of pericyte specific R-Ras. Fluorescently labeled, ex-vivo-transduced pericytes were implanted with VEGF-containing Matrigel into the flank of R-Ras KO mice. Matrigel plugs were examined 7 days later (indicated by dashed lines) (G). Histological analysis of the plugs (H). The ex vivo-transduced, implanted pericytes were visualized by green fluorescence. Microvessels were stained with CD31 (red). Scale bars, 100 µm (H), 50 µm (D). *p < 0.05, ±SEM. See also Figure S4.