RT Journal Article SR Electronic T1 Ex vivo observation of granulocyte activity during thrombus formation JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.13.199174 DO 10.1101/2020.07.13.199174 A1 Daria S. Morozova A1 Alexey A. Martyanov A1 Sergei I. Obydennyi A1 Julia-Jessica D. Korobkin A1 Alexey V. Sokolov A1 Ekaterina V. Shamova A1 Irina V. Gorudko A1 Anna Shcherbina A1 Mikhail A. Panteleev A1 Anastasia N. Sveshnikova YR 2020 UL http://biorxiv.org/content/early/2020/07/13/2020.07.13.199174.abstract AB Infiltration of growing thrombi by leukocytes, being the key part of the thromboinflammation, is well established in vivo. The study was aimed at the development of an ex vivo simulation of this phenomenon. Thrombus formation in anticoagulated whole blood from healthy volunteers and patients was visualized by fluorescent microscopy in parallel-plate flow chambers with fibrillar collagen type I coverslips.Moving CD66b-positive cells (granulocytes) were observed in hirudinated or recalcified blood under low wall shear rate conditions (<200 s−1). These cells crawled around thrombi in a step-wise manner with an average rate of 70 nm/s. Pre-incubation of blood with leukocyte priming agents lead to a significant increase in average cell velocity. On the contrary, leukocytes from Wiskott-Aldrich syndrome patients demonstrated a 1.5-fold lower average velocity, in line with their impaired actin polymerization.Thereby, the observed features of granulocytes crawling are consistent with the neutrophil chemotaxis phenomenon. We conclude that the proposed ex vivo experimental setting allows us to observe granulocytes activity in near-physiological conditions.Competing Interest StatementThe authors have declared no competing interest.MPOmyeloperoxidaserLfrecombinant lactoferrinLPSlipopolysaccharides from E. coli O111:B4vWFvon Willebrand factorPSphosphatidylserineGPglycoproteinCDcluster of differentiationFOVfield of viewWASWiskott-Aldrich syndrome.