Increased β integrin expression in the human and mouse elastin mutant aorta. (A–C) Transverse aortic sections of wild-type and elastin mutant littermates at E16.5 or P1.5 stained for SMA and nuclei (DAPI) and for either integrin β3 (A and B) or β1 (C). CD31 staining is also included in B. The boxed region of Eln^(−/−) aorta in C is shown as an inset without DAPI staining. Note that β3 expression is increased in the SMCs of the Eln mutant aortas, particularly in subendothelial layers of Eln^(−/−), and β1 expression is up-regulated in ECs and many SMCs, primarily in the outer smooth muscle layers in Eln^(−/−) aorta. For each genotype, n = 3 pups in A and C and n = 4 pups in B. (D and E) β1 and β3 transcript levels normalized to Gapdh as measured by qRT-PCR of cDNAs from aortas of specified elastin genotype at P0.5; n = 3 in duplicate. (F) Representative images of aortic sections of WBS patients (age 5 mo) and age-matched human controls stained for SMA, activated β3, and nuclei (DAPI); n = 3 patients. SVAS is the major cause of morbidity in WBS patients. (G and H) Protein levels of β3 and GAPDH in iPSC-SMCs derived from SVAS or control patients were assayed by Western blot with densitometric analysis of β3 normalized to GAPDH; n = 2. Data are presented as mean ± SD. ANOVA was used in D and E, and Student’s t test in H. *, P < 0.05; **, P < 0.01. Lu, aortic lumen. Bars: (A, B, F, and inset in C) 10 µm; (main images in C) 100 µm.