E-cigarettes clobber platelets as much as cigarettes

One of the main ways that smoking increases the risk of heart disease is by activating platelets, cells in blog that stick together and form blood clots.  When you cut yourself, this is a good thing, because it stops bleeding.  When platelets are activated inappropriately, they stick to the lining of arteries (the endothelium) and tear it up.  When a blood clot floating around in your blood stream blocks an artery in your heart it causes a heart attack; when it blocks an artery in your brain is causes a stroke. 
 
Sara Hom and colleagues at the State University of New York, recently published “Platelet activation, adhesion, inflammation, and aggregation potential are altered in the presence of electronic cigarette extracts of variable nicotine concentrations,” which exposed human blood platelets to extracts from conventional cigarette smoke and e-cigarette aerosol.  They found that both stimulated platelet activation and that this effect is due to the ultrafine particles in both, not the nicotine.
 
They sum their results up nicely in their paper:
 

Our findings suggest that e-vapor extracts pose a similar risk to as conventional tobacco products. This is an important finding since the effects of e-cigarettes, which are increasing in popularity, remain to be virtually untested. Another important finding from this work is that platelet activities were not a function of nicotine concentration. Overall, our findings suggest it is not nicotine or toxic combustion product that activates the hemostatic system, but instead the hemostatic system is most responsive to fine particulate matter. Importantly, it has been shown that the concentration of fine particulate matter in e-vapor is in the same range as the fine particulate matter found in mainstream/sidestream tobacco smoke.

 
This study is an important addition to the evidence that e-cigarettes are as dangerous as conventional cigarettes for heart disease.  Because, like cigarettes and e-cigarettes, heat-not-burn products like Philip Morris’s iQOS system also deliver the nicotine as an aerosol of ultrafine particles, I would expect similar effects on platelets and heart disease risk.
 
Here is the abstract:
 

Tobacco smoke extracts prepared from both mainstream and sidestream smoking have been associated with heightened platelet activation, aggregation, adhesion, and inflammation. Conversely, it has been shown that pure nicotine inhibits similar platelet functions. In this work, we 1) evaluated the effects of e-cigarette extracts on platelet activities and 2) elucidated the differences between the nicotine-dependent and non-nicotine dependent (e.g. fine particulate matter or toxic compounds) effects of tobacco and e-cigarette products on platelet activities. To accomplish these goals, platelets from healthy volunteers (n = 50) were exposed to tobacco smoke extracts, e-cigarette vapor extracts, and pure nicotine and changes in platelet activation, adhesion, aggregation, and inflammation were evaluated, using optical aggregation, flow cytometry, and ELISA methods. Interestingly, the exposure of platelets to e-vapor extracts induced a significant up-regulation in the expression of the pro-inflammatory gC1qR and cC1qR and induced a marked increase in the deposition of C3b as compared with traditional tobacco smoke extracts. Similarly, platelet activation, as measured by a prothrombinase based assay, and platelet aggregation were also significantly enhanced after exposure to e-vapor extracts. Finally, platelet adhesion potential toward fibrinogen, von Willebrand factor, and other platelets was also enhanced after exposure to e-cigarette vapor extracts. In the presence of pure nicotine, platelet functions were observed to be inhibited, which further suggests that other constituents of tobacco smoke and electronic vapor can antagonize platelet functions, however, the presence of nicotine in extracts somewhat perpetuated the platelet functional changes in a dose-dependent manner.

 
The full citation is:  Hom S, Chen L, Wang T, Ghebrehiwet B, Yin W, Rubenstein DA.  Platelet activation, adhesion, inflammation, and aggregation potential are altered in the presence of electronic cigarette extracts of variable nicotine concentrations.  Platelets. 2016 Nov;27(7):694-702. Epub 2016 Apr 20.