Project summary The main objective of this project is to investigate the feasibility of using a novel peripheral biomarker—the metal cargo of circulating brain-derived extracellular vesicles (EVs)—to assess non-invasively metal deposition in brain due to e-cigarette aerosol exposure. This project is a supplement to an ongoing R01, which investigates the neurotoxic, behavioral and pathological consequences of metal exposure and metal dyshomeostasis in mice exposed to e-cigarette aerosol. The candidate for this supplement is a US citizen of Haitian descent. She graduated from Barnard College with a B.A. degree in Environmental Science and a minor in Biology. Her enrollment into our MS program at Columbia University in the Fall of 2022 will increase the representation of Black women in science, which is particularly lacking. For her research and training, she will be mentored by Drs. Diane Re and Markus Hilpert, MPIs of the parent grant, and she will receive additional mentorship from Dr. Ana Navas-Acien who is part of the e-cigarette working group at Columbia University. In the proposed project, the candidate will (1) determine whether metal content in blood brain-EVs is a longitudinal biomarker of e-cigarette exposure and brain metal elimination upon exposure to e-cigarette aerosol, (2) investigate whether brain EV metal levels can be used to non-invasively infer metal burden in the brain of e-cigarette exposed mice, and (3) explore whether genetic susceptibility to Parkinson's disease (PD) modifies brain EV metal content. Through the proposed analyses, the candidate will gain experience and skills in: 1) the use of novel EV biomarkers to study the effects of metal exposure from e-cigarette use on neurodegenerative disease, 2) statistical analysis of the novel biomarker data; 3) training in animal models of environmental exposures, and 4) understanding the mechanisms of toxic metal exposure from e-cigarette use on metal homeostasis in the brain and neurodegenerative disease. The candidate will also receive formal training by taking courses through our MS program during the regular school year. The candidate and mentors will meet once a week for training and to discuss progress. This project could validate the first brain-relevant peripheral biomarker to predict brain metal load of subjects exposed to e-cigarette aerosol. Based on this study, brain EV metal load could become an established biomarker of individual neurotoxic risk for vapers and second-hand exposure. The proposed research has also significant implications for intervention studies to reduce adverse effects of e-cigarette aerosol exposure. Finally, by providing advanced skills, training and laboratory research opportunities to a Master of Science student with focus in toxicology, this project will enhance diversity in our research team at Columbia University and down the road in the fields of toxicology and environmental health sciences.