Fig 1: HGPS iPSC‐EC angiogenic incompetence is eNOS‐dependent. (a) Fluorescence images of NO, measured by DAF‐FM staining, were generated in normal and HGPS ECs either untreated or treated with 0.25 mM nitric oxide donor SNAP, and with 0.2 mM L‐NAME, an eNOS inhibitor (scale bars = 200 μm). (b) Quantification of the DAF‐FM fluorescence intensity for intracellular NO level in normal and HGPS iPSC‐ECs. (c) Matrigel‐based tube formation assay to assess the angiogenic activity of normal and HGPS iPSC‐ECs either untreated or treated with 0.25 mM SNAP, and with 0.2 mM L‐NAME (scale bars = 200 μm). (d) Quantification of tube length per field; n, nine fields per group. (e) Western blotting analysis with indicated antibodies on the lysates of normal and HGPS iPSC‐ECs. (f) Quantification of fold change for Western blot band densitometry of HGPS MMP and TIMP levels normalized to healthy control. DAF‐FM, 4‐amino‐5‐methylamino‐2’,7’‐difluorofluorescein diacetate; SNAP, S‐Nitroso‐N‐acetyl‐DL‐penicillamine; L‐NAME, N‐omega‐nitro‐L‐arginine methyl ester hydrochloride. Data are presented as mean ±SEM, *p < 0.05; **p < 0.01, ***p < 0.001, ****p < 0.0001; n, 3 independent experiments