Effects of cigarettes and e-cigarettes on platelet function

: development of novel methods to assess the effect of chronic exposure.

Abstract

The usage of e-cigarettes in rising, not only in smokers looking to quit but also in young people
and previously non-smokers. Evidence suggests e-cigarettes might not be as safe as once
expected and a contributor to cardiovascular disease. With platelets being a known factor in
cardiovascular disease it is essential on furthering the understanding of their effects on
platelets. A major issue in this regard is most studies on toxicology need cohort studies and
because uptake of e-cigarettes is relatively new these are lacking, thus we need to find
alternative methods for studying these potentially harmful effects. This thesis demonstrates
cigarette and e-cigarette extracts induces an agonist specific prothrombotic phenotype. This
mechanism appears to be nicotine-independent in regard to e-cigarettes, as it is observed in
the nicotine-free e-cigarette abstract. We were unable to discern the mechanism for this. We
were able to ascertain that for cigarettes, this pathway impacts dense granule secretion but
not calcium mobilisation, while e-cigarettes likely work via a distinct pathway that has been
shown to impact both dense granule and calcium mobilisation. We also demonstrated a novel
method for the research of toxicological substances on platelets, using a novel megakaryocyte
culture and platelet generation method to allow us to see if exposure on the megakaryocyte
has any impact on the number and function of produced platelets. Ultimately, we found that
megakaryocytes cultures with e-cigarette and cigarette exposure do not lead to a difference
in the ability of megakaryocytes to produce platelets or in the function of the platelets they
generate. However, such a method would allow for a genotype to phenotype analysis when
examining chronic toxicological studies in a platelet context with further optimisation. It was
also demonstrated that it can efficiently produce megakaryocytes from a genetically flexible
source, which can generate an adequate quantity of platelets for comprehensive functional
analysis. This was done by utilising mouse embryonic stem cells as a source for
megakaryocytes, a cell type that is easily genetically modifiable, allowing for studies to fully
understand the impacts of genetics on platelet production and function in any gene. I am
confident this work furthers the understanding of e-cigarettes and cigarettes on platelet
function while also offering novel methods for the study of platelets that could have great
utility in many avenues of research.

Date of Award	19 Mar 2024
Original language	English
Awarding Institution	University of Bristol
Supervisor	Alastair W Poole (Supervisor) & Ingeborg Hers (Supervisor)