Electronic cigarette extract induced toxic effect in iPS-derived cardiomyocytes.BACKGROUND
 Cigarette smoking is an important risk factor for cardiac diseases.  In the current study, we sought to assess the effect of electronic cigarette extract (ECE) and conventional cigarette smoke extract (CSE) on cardiomyocytes.


 iPSCs-derived cardiomyocytes were used in the study to evaluate cellular toxicities.  Cells were exposed to either ECE or CSE for two consecutive days as an acute exposure or every other day for 14 days.  Concentration of nicotine in both ECE and CSE were measured by Mass-Spectrometry and Q-Exactive-HF was used to identify other ingredients in both extracts.  Fluorescent microscopy was used to measure the oxidative stress after ECE and CSE exposure.  Motility and beat frequency of cardiomyocytes were determined using the Sisson-Ammons Video Analysis system.  Heart failure target panel genes of exposed cardiomyocytes were compared to control unexposed cells.


 Despite nicotine concentration in CSE being six-fold higher than ECE (50 μg in CSE and 8 μg in ECE), ECE had similar toxic effect on cardiomyocytes.  Both CSE and ECE generate significant cellular reactive oxygen species.  The Sisson-Ammons Video Analysis (SAVA) analysis showed significant changes in myocyte function with both CSE and ECE slowing beating and increasing cell death.  Chronic exposure of both ECE and CSE significantly decreased cardiomyocytes viability long term at all doses.  Target panel gene expression profiles of both ECE and CSE exposed cardiomyocytes were different from controls with distinct pattern of genes that involved cell proliferation, inflammation, and apoptosis.


 CONCLUSION
 ECE and CSE produce similar cardiomyocyte toxicities which include generating oxidative stress, negative chronotropic effects, adverse changes in myocardial gene expression and ultimately cell death.
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