Blood collection and separation of neutrophils
Venous blood samples (10 ml) obtained from the patients with ischemic stroke and healthy controls were collected in ethylene diamine tetraacetic acid anticoagulant vacuum tubes at admission. Blood samples were fractionated through centrifugation at 3000 × g for 10 min at 4°C. Next, the plasma layer was aliquoted and stored at -80°C for routine lab assays. Neutrophils were separated using a standard Ficoll‐Paque Plus gradient method for RNA extraction and examination as previously described(G. Li, Ma, et al., 2018).