Fig. 6.

Lysyl oxidase-like 2 (LOXL2) promotes aortic matrix stiffness and vascular smooth muscle cell (VSMC) stiffness in aging. A: passive compliance of the carotid artery, measured by pressure myography, aged [old (O)] wild-type (WT; 15 mo old, n = 7; 3 female, 4 male), young (Y) WT (3–4 mo old, n = 10; 5 female, 5 male), young LOXL2^+/− (3-4 mo old, n = 12; 7 female, 5 male) and aged LOXL2^+/− (15 mo old, n = 12; 7 female, 5 male) mice (*P < 0.05 by Kruskal-Wallis test with Dunn’s correction). Bi and Bii: tensile testing of intact (Bi) and decellularized (Bii) aortic segments of WT and littermate LOXL2^+/− mice. Data are shown as means (solid line) ± SE (broken lines) (n = 12 LOXL2^+/− and n= 8 WT mice; ***P < 0.0001 by Wilcoxon rank sum test). C: LOXL2 expression in the conditioned media and cell-derived ECM of endothelial and smooth muscle cells isolated from LOXL2^+/− and littermate WT mouse aorta; GAPDH is shown as a reference control. Blot is representative of 5 independent experiments. IB, immunoblot. D: stiffness of mouse aortic smooth muscle cells isolated from old (15 mo old) WT and LOXL2^+/− littermate mice measured by magnetic torsion cytometry (n = 543 WT cells; 165 LOXL2^+/− cells; *P < 0.05 by Student’s t-test). E: cytoskeletal remodeling dynamics of aortic smooth muscle cells from old (15 mo old) WT and littermate LOXL2^+/− mice (n = 599 WT cells, 586 LOXL2^+/− cells; ****P < 0.05 by Student’s t-test). MSD, mean square displacement. F: motility of WT- and LOXL2-depleted VSMC examined by transwell migration assay using 10% serum as chemoattractant (n = 6; **P < 0.01 by 2-way ANOVA). RFU, relative fluorescence units. G: deadhesion dynamics of WT- and LOXL2-depleted VSMCs using 0.05% trypsin (n = 5; ****P < 0.0001 by Wilcoxon rank sum test).