Comparison of the Cytotoxic Potential of Cigarette Smoke and Electronic Cigarette Vapour Extract on Cultured Myocardial Cells

Abstract

Background: Electronic cigarettes (ECs) have been marketed as an alternative-to-smoking habit. Besides chemical studies of the content of EC liquids or vapour, little research has been conducted on their in vitro effects. Smoking is an important risk factor for cardiovascular disease and cigarette smoke (CS) has well-established cytotoxic effects on myocardial cells. The purpose of this study was to evaluate the cytotoxic potential of the vapour of 20 EC liquid samples and a “base” liquid sample (50% glycerol and 50% propylene glycol, with no nicotine or flavourings) on cultured myocardial cells. Included were 4 samples produced by using cured tobacco leaves in order to extract the tobacco flavour. Methods: Cytotoxicity was tested according to the ISO 10993-5 standard. By activating an EC device at 3.7 volts (6.2 watts—all samples, including the “base” liquid) and at 4.5 volts (9.2 watts—four randomly selected samples), 200 mg of liquid evaporated and was extracted in 20 mL of culture medium. Cigarette smoke (CS) extract from three tobacco cigarettes was produced according to ISO 3308 method (2 s puffs of 35 mL volume, one puff every 60 s). The extracts, undiluted (100%) and in four dilutions (50%, 25%, 12.5%, and 6.25%), were applied to myocardial cells (H9c2); percent-viability was measured after 24 h incubation. According to ISO 10993-5, viability of <70% was considered cytotoxic. Results: CS extract was cytotoxic at extract concentrations >6.25% (viability: 76.9 ± 2.0% at 6.25%, 38.2 ± 0.5% at 12.5%, 3.1 ± 0.2% at 25%, 5.2 ± 0.8% at 50%, and 3.9 ± 0.2% at 100% extract concentration). Three EC extracts (produced by tobacco leaves) were cytotoxic at 100% and 50% extract concentrations (viability range: 2.2%–39.1% and 7.4%–66.9% respectively) and one (“Cinnamon-Cookies” flavour) was cytotoxic at 100% concentration only (viability: 64.8 ± 2.5%). Inhibitory concentration 50 was >3 times lower in CS extract compared to the worst-performing EC vapour extract. For EC extracts produced by high-voltage and energy, viability was reduced but no sample was cytotoxic according to ISO 10993-5 definition. Vapour produced by the “base” liquid was not cytotoxic at any extract concentration. Cell survival was not associated with nicotine concentration of EC liquids. Conclusions: This study indicates that some EC samples have cytotoxic properties on cultured cardiomyoblasts, associated with the production process and materials used in flavourings. However, all EC vapour extracts were significantly less cytotoxic compared to CS extract.

Evaluation of Electronic Cigarette Liquids and Aerosol for the Presence of Selected Inhalation Toxins

“…In fact, the Flavors and Extracts Manufacturers' Association (FEMA) has issued an official statement mentioning that flavor ingredients are evaluated for exposure through ingestion only; thus, any results cannot be extrapolated to use through inhalation. 5 Studies have shown that any cytotoxic properties of e-cigarette liquids and aerosol, although significantly lower than tobacco smoke, may be attributed to specific flavors, [6][7][8] indicating that further research is certainly needed in this area.…”

Analysis of electronic cigarette use among Polish dental students

“…To date, there is an increasing number of publications concerning the influence of electronic cigarettes on the human body, as well as literature comparing traditional and electronic smoking. What is more, Farsalinos et al 17 showed that cinnamon-flavored liquids have a cytotoxic influence on myoblasts isolated from rats' hearts. Furthermore, Yu et al 18 presented findings of changes in the DNA which resulted from e-cigarette aerosol, which were similar to those caused by tobacco smoke.…”

Electronic Cigarette

“…Sağlıklı sigara içici-lerinde e-sigara kullanımını takiben beş dakika içinde havayolu rezistansının, empedansın ve oksidatifstresin arttığı gösterilmiştir (24) . Ratların kardiyak myoblast hücre kültüründe beş farklı e-sigara üreticisinin 20 refill solüsyonundaki çeşitli tatlandırıcıların sitotoksik olduğu (25) ; klinik deneylerde ise e-sigaraların sistolik ve diyastolik kan basıncını yükselttiği kalp hızını artırdığı (26) gösterilmiştir.…”