Proteomic analysis of tissue-derived extracellular vesicles shows region-specific molecular changes in a rat model of takotsubo syndrome.

Takotsubo syndrome (TS) is characterized by transient regional wall motion abnormalities (RWMA) of the heart following stress. Extracellular vesicles (EVs) play a significant role in cellular communication and disease pathophysiology, but remain unexplored in TS. Using a high-fidelity rat model of TS induced by isoprenaline infusion (n = 16), we isolated EVs from the tissue of affected apical and unaffected basal segments of the left ventricle at 24 h post-induction. The TS phenotype and cardiac function were assessed using high-resolution echocardiography. EVs were characterized by electron microscopy, western blot, and nanoparticle tracking analysis (NTA). Moreover, EV protein analysis was performed using tandem mass tag (TMT) proteomics. Pure, cup-shaped vesicles ranging from 50 to 500 nm were successfully isolated. NTA revealed lower particle concentrations in EVs isolated from the apex of TS24h hearts compared to their corresponding basal segments. Western blot experiments confirmed the presence of typical EV markers, including Flotillin 1, TSG101, and CD63. We identified 2093 proteins, with 238 differentially expressed (|FC| > 0.58, adj.P < 0.05) proteins between TS-apex and control-apex, and 562 between TS-apex and TS-base, indicating a unique molecular adaptation in the affected apex. Functional enrichment analysis showed increased abundance of proteins associated with immune response, tissue repair, and survival signalling pathways. Proteins related to mitochondrial function showed decreased abundance. Network analysis revealed an association between proteins involved in lipid processes and inflammation. Overall, this study presents the first proteomic characterization of EVs in TS hearts. Our results demonstrate a distinct EV protein abundance profile in the affected apical segments of TS hearts, with marked changes in proteins related to inflammatory responses, tissue repair mechanisms, energy metabolism, and cell survival pathways. This comprehensive proteomic profile of EVs in TS hearts provides potential candidates for therapeutic targets and diagnostic biomarkers, warranting further mechanistic and clinical validation studies.