Platelets are responsible for the accumulation of β-amyloid in blood clots inside and around blood vessels in mouse brain after thrombosis

Introduction: Platelets contain beta-amyloid precursor protein (APP) as well as A beta peptide (A beta) that can be released upon activation. During thrombosis, platelets are concentrated in clots and activated. Methods: We used in vivo fluorescent analysis and electron microscopy in mice to determine to what degree platelets are concentrated in clots. We used immunostaining to visualize A beta after photothrombosis in mouse brains. Results: Both in vivo results and electron microscopy revealed that platelets were 300-500 times more concentrated in clots than in non-clotted blood. After thrombosis in control mice, but not in thrombocytopenic animals, A beta immunofluorescence was present inside blood vessels in the visual cortex and around capillaries in the entorhinal cortex. Conclusion: The increased concentration of platelets allows enhanced release of A beta during thrombosis, suggesting an additional source of A beta in the brains of Alzheimer's patients that may arise if frequent micro-thrombosis events occur in their brains. (C) 2016 The Authors. Published by Elsevier Inc.