Thrombo-inflammatory diseases, such as ischemic stroke, are major causes of death and disability worldwide.
The distinct molecular mechanisms how platelets contribute to thrombo-inflammatory processes remain largely unknown. We could already demonstrate that platelet secretion is an important mediator of thrombo-inflammation in the ischemic brain. Moreover, targeting the early steps of platelet adherence to the vessel wall via glycoprotein (GP)Ib/von Willebrand factor (VWF) interactions not only reduced thrombus burden in the cerebral microvasculature, but also limited the local inflammatory response in the ischemic organ. Besides platelets, also endothelial cells (the major component of the blood brain barrier) and leukocytes, in particular T cells, play a central role in ischemia/reperfusion (I/R) injury. Accordingly, lack of T cells results in dramatically reduced infarct sizes.
To develop novel treatment strategies, it is necessary to understand the detrimental interplay between thrombotic and inflammatory circuits, which would only be possible if the cellular interactions can be visualized. In order to image thrombo-inflammation with different advanced imaging modalities, we collaborate intensively with the Bio-Imaging Center. Together, we have established optical clearing and labelling protocols for light-sheet-fluorescence microscopy (LSFM), which allows us to visualize the whole vascular tree and the localization of platelets and/or immune cells within the brain vasculature in a whole organ setting. In addition, we benefit from confocal and two-photon intravital microscopy to image dynamic interactions within the ischemic organ with a high temporal and spatial resolution. Our complementary approaches will provide a better understanding of the pathomechanisms, taking place in the vascular compartment, which lead to organ damage following I/R injury.
The established imaging techniques are not only used to study thrombo-inflammation in the brain vasculature, but are also utilized to study other dynamic processes like for example the production of platelet in the bone marrow (thrombopoiesis).