Introduction: Neutrophil extracellular traps (NETs) are composed mainly of strands of filamentous DNA and nuclear proteins, such as chromatin or isoforms of histone and secretable neutrophil granular proteins. Recent studies have shown that NETs existed in the venous thrombi and might function as a scaffold and had implication for thrombolytic treatments.
Hypothesis: NETs also exists in cerebral arterial thrombus collected from patients with acute ischemic stroke(AIS).
Methods: Ten arterial thrombi were collected from 10 AIS patients (33-78 years old, 4 females) who were treated by endovascular therapy (eight of them accepted alteplase thrombolysis firstly)within 8 hours after symptoms onset. Hematoxylin-eosin (HE) staining, immunofluorescence staining (including anti-histone H3 and Hoechst 33342 which label DNA) and electron microscopy were performed to identify the existence of fibrin and/or NETs in thrombus.
Results: There were 4 thrombi from middle cerebral artery, 3 from internal carotid artery and 3 from basilar artery. Cardioembolism were considered as etiology for 5 patients and large artery atherosclerosis was the etiology for another 5 patients. HE staining showed that large amounts of fibrin and white blood cells in all ten cerebral arterial thrombi. NETs structures were also identified in 10/10 cerebral arterial thrombi by immunofluorescence staining. Furthermore, the existence of neutrophil-released DNA network together with fibrin was confirmed using electron microscopy in all 10 thrombi.
Conclusion: Our results directly demonstrated that NETs do exist in the arterial thrombi from patients with AIS. they may serve as another structural component in addition to fibrin in both cardiogenic and artery atherosclerotic thrombi. NETs can be a new potential target for the recanalization treatment.
Keyword: Neutrophil extracellular traps (NETs); arterial thrombus; Acute ischemic stroke