iPSC-ECs were incubated with 10% serum from nonsmokers (n=5), e-cigarette users (n=4), and cigarette smokers (n=5) for 48 hours. (A) Intracellular ROS production in iPSC-ECs treated with sera collected from nonsmokers, e-cigarette users, or cigarette smokers at baseline. (B) Serial changes of ROS production in iPSC- ECs treated with serum collected from smokers before (−1 hours; shown in detail in A) and after (0, 1, and 3 hours) smoking. (C) iPSC-ECs (1 × 104) treated with serum samples from nonsmokers or smokers were seeded onto μ-Slide Angiogenesis containing Matrigel® Basement Membrane Matrix for 16 hours, and the formation of capillary-like structures were then imaged by phase-contrast microscopy (x 20) and quantified. Data are represented as mean ± SD. *p < 0.05 and **p < 0.001, compared to nonsmokers or baseline; and #p < 0.05, compared to pre-smoking within each group.