Introduction: Extracellular vesicles (EV) including microvesicles, microparticles and exosomes are now being recognized as key players in cardiovascular/metabolic diseases, hemostasis and thrombosis. Platelet-derived EVs are particularly important in mediating thrombotic events, whereas monocytes-associated EVs are known to increase inflammation, which can potentiate and exacerbate platelet activation and platelet-leukocyte aggregation. However, the signature of EVs in the db/db mice with metabolic syndrome (MetS) is yet to be established.
Hypothesis: EV numbers or phenotype differ between the control db/+ mice and db/db mice that are procoagulant.
Methods: Platelet poor plasma (PPP) was collected from adult db/+ and db/db mice subjected to experimental stroke via distal middle cerebral artery occlusion or sham surgery. PPP was tested by flow cytometry using panels of antibodies to detect EVs derived from leukocytes (CD11b), neutrophils (Ly6G), platelets (CD41), and RBCs (Ter119), as well as those expressing the oxidized LDL receptor CD36. The rate of clot formation and maximum clot firmness of whole blood was determined using thromboelastography for the intrinsic and extrinsic pathways.
Results: No significant differences were seen in total EV counts or those bearing CD36, CD11b, or Ter119 between genotypes. However, PMN and platelet-derived EV counts were higher in db/db mice compared to db/+ mice. RBC-derived EVs were higher in mice post-stroke, likely reflecting fragmentation of RBCs during the clotting process. PPP from db/db mice accelerated the coagulation of blood from db/+ mice and increase their clot strength.
Conclusions: The plasma of db/db mice is procoagulant and with higher levels of platelet-derived and proinflammatory EVs, which may underlie the impaired retrograde collateral flow and poor outcome after ischemic stroke. Ongoing studies will investigate the causal relationship between EVs and the thrombophilia tendency observed in those with type 2 diabetes.