C0228: Platelet Thromboxane A2 is an Extracellular Mediator of the Prothrombotic Effect of Erythrocytes

Abstract

Background: The thrombotic cellular mechanisms associated with cardiovascular events remains unclear, largely because of an inability to visualize thrombus formation. In addition, the contribution of endothelial cell (EC) injuries to thrombus formation processes are unclear. Methods: We developed in vivo fluorescent imaging technique based on singleand multi-photon microscopy to revealed the multicellular processes during thrombus development. We utilized multi-color and high-speed resonance scanner systems, and applied to fluorescent protein transgenic mice. We could identify single platelet kinetics in developing thrombus in living animals. Results: We assessed dynamic cellular interplay in two thrombosis models. First, we visualized that rapidly developing thrombi composed of discoid platelets without EC disruption was triggered by reactive oxygen species by photochemically induction from moderate power laser irradiation. In this model, thrombus consisted by discoid platelet aggregations without leukocyte recruitment. The other model is, thrombus with EC disruption. High power laser induced EC erosion and extravasations of circulating leukocytes with thrombus development. Inflammatory cytokine, adhesion molecules dynamically control these two processes. As for the thrombus formation with EC disruption, chemokine expressions in endothelium and leukocyte (especially neutrophils) recruitment played a significant role in these processes. TLR4 signalling also contributed to these steps. Conclusions: In sum, using our imaging system can be a powerful tool to analyze thrombus formation and evaluate the therapeutic strategies.