Platelet-Released Extracellular Vesicle Characteristics Differ in Chronic and in Acute Heart Disease

Extracellular vesicles (EVs), shed in response to cell activation, stress, or injury, are increased in the blood of patients with cardiovascular disease. EVs are characterized by expressing parental-cell antigens, allowing the determination of their cellular origin. Platelet-derived EVs (pEVs) are the most abundant in blood. Although not universally given, EVs generally express phosphatidylserine (PS) in their membrane.

To investigate pEVs in chronic and acute conditions, such as chronic heart failure (CHF) and first-onset acute coronary syndrome (ACS), in patients treated as per guidelines.

EVs in CHF patients (n = 119), ACS patients (n = 58), their respective controls (non-CHF [n = 21] and non-ACS [n = 24], respectively), and a reference control group (n = 31) were characterized and quantified by flow cytometry, using monoclonal antibodies against platelet antigens, and annexin V (AV) to determine PS exposure.

CHF patients had higher EVs-PS^- numbers, while ACS had predominantly EVs-PS⁺. In contrast to ACS, CHF patients had significantly reduced numbers of pEVs carrying PECAM and α_IIb-integrin epitopes (CD31⁺/AV⁺, CD41a⁺/AV⁺, and CD31⁺/CD41a⁺/AV⁺), while no differences were observed in P-selectin-rich pEVs (CD62P⁺/AV⁺) compared with controls. Additionally, background etiology of CHF (ischemic vs. nonischemic) or ACS type (ST-elevation myocardial infarction [STEMI] vs. non-STEMI [NSTEMI]) did not affect pEV levels.

PS exposure in EV and pEV-release differ between CHF and ACS patients, with tentatively different functional capacities beyond coagulation to inflammation and cross-talk with other cell types.