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