Pharmacological blockade of β3 attenuates Eln^(−/−) aortic hypermuscularization and stenosis. (A) Aortas were harvested from Eln^(−/−) embryos at E15.5 and fixed either immediately or after culturing as explants for 18 h in the presence of an isotype control IgG1 or an integrin αvβ3–blocking antibody. Transverse sections were stained for SMA, CD31, and nuclei (DAPI). (B and C) Eln^(−/−) aortas cultured for 18 h and sectioned and stained as in A were used to calculate the lumen and media wall areas; n = 3 aortas, 3 sections per aorta. (D–H) Female and male Eln^(+/−) mice were crossed, and pregnant dams were implanted with miniature osmotic pumps containing integrin β3 inhibitor cilengitide or vehicle (PBS) at E13.5. (D) Transverse aortic sections of wild-type, Eln^(+/−), and Eln^(−/−) pups at P0.5 were stained as in A and used to measure lumen and media wall area as shown in E and F; n = 3 aortas per genotype, 3 sections per aorta. (G) High magnification images of vehicle- or cilengitide-treated wild-type and Eln^(−/−) aortas at P0.5 were sectioned and stained as in A, and arrowheads indicate examples of radially oriented SMCs. These images were used to quantify the SMC nucleus orientation in the inner three layers of aortic media (H); per each genotype + cilengitide/vehicle group, n = 3 aortas, and >275 SMCs were scored. Data are presented as mean ± SD. ANOVA was used. *, P < 0.05; ** P < 0.01; ***, P < 0.001. Lu, aortic lumen. Bars: (A and D) 100 µm; (G) 10 µm.