Role of Platelets in Abdominal Aortic Aneurysm Formation and Progression: New Aspects from Experimental and Clinical Approaches.

Abdominal aortic aneurysm (AAA) is a vascular disease with an atherosclerotic background resulting in progressive abdominal aortic dilation. The mechanisms of AAA progression include chronic inflammation within the aneurysm segment, reinforcing extracellular matrix degradation, and weakening of the aortic vessel wall. Platelets are essential mediators of hemostasis and play a dominant role in cardiovascular disease. Recent data suggest a pivotal role of platelets in AAA formation and progression by dysregulated platelet activation. These findings include a potential crosstalk of platelets with different cell types such as macrophages and fibroblasts, which amplifies the inflammatory response within the aortic tissue and promotes aortic wall stiffening. Experimental studies provided evidence for platelets to directly contribute to AAA formation and progression via the collagen receptor glycoprotein VI by promoting vascular inflammation, as well as aortic wall remodeling. Moreover, platelet and red blood cell interactions via the TSP-1-CD36 axis reinforces aneurysm formation via elevated procoagulant activity of both cells in experimental mice and AAA patients. Therefore, platelets and a platelet-mediated cellular crosstalk play a crucial role in AAA by promoting the development and progression of AAA. To date, no therapeutic treatment is available and surgical repair is the only option to prevent patients from aortic rupture. Thus, there is a strong need for an effective therapy to attenuate AAA progression. This review highlights the mechanisms of platelet activation and the relevance for the identification of new platelet-derived targets to develop a drug-based therapy for AAA patients.