Abstract P3151: A Unique Profile Of Extracellular Vesicles In Marfan Patients With Thoracic Aortic Aneurysm

Objectives: Extracellular vesicles (EVs) [exosomes and microvesicles] have significant diagnostic and therapeutic potential, but clinical application is limited by disparate methods of data collection. Exosomes are 30-100nm, and microvesicles are 100-300nm lipid bilayer vesicles that originate from all cell types. Marfan Syndrome (MFS) is a connective tissue disorder. Thoracic aortic aneurysm (TAA) formation and dissection are the leading causes of death in MFS patients. Early identification of TAAs in MFS patients is imperative and will mitigate morbidity and mortality. This study’s goal was to develop a reproducible workflow for isolation and quantification of EVs 30-300nm and test the hypothesis that number and size distribution are altered in MFS patients with TAA. Methods: A method of standardized reproducible measurement of EVs isolated from plasma was developed. This includes isolation by automated size exclusion chromatography and quantification of size distribution by tunable resistive pulse sensing. Characteristic markers specific to both EV subtypes were confirmed by immunoblot. Results: EVs isolated from control plasma (n=12) and Marfan TAA plasma (n=6) were measured for concentration (control 0.60 x 10 11 particles/mL, MFS TAA 1.47 x 10 11 particles/mL), mean diameter (control 77.75nm, MFS TAA 69.92nm), mode diameter (control 65.50nm, MFS TAA 60.50nm), and d90/d10 ratio (control 1.68, MFS TAA 271 1.57). Conclusion: MFS patients with TAA have more EVs with a smaller diameter, suggesting increased export and a shift in ratio of microvesicles:exosomes. This may be used as a diagnostic tool or potential therapeutic target. This scalable protocol ensures recovery of intact EVs suitable for downstream biochemical and functional analyses. Simultaneous measurement quantifies EV concentration and size distribution absolutely, correcting for variations, providing a novel method of standardization.