CD41⁺ extracellular vesicles produced by avian thrombocytes contain microRNAs

Avians have thrombocytes in their blood circulation rather than mammalian platelets. However, many details of thrombocyte characteristics have not been determined. Here, chicken thrombocytes were isolated, and extracellular vesicle (EV) production was investigated. The thrombocyte-specific markers cd41 and cd61 were expressed in the yolk sac at 24 h. According to the embryonic developmental stage, the cd41-expressing tissues changed from the yolk sac to the bone marrow and spleen. Accordingly, the bone marrow and spleen were the main tissues producing thrombocytes in adult chickens. Avian thrombocytes were separated from adult spleen cells through a combination of discontinuous density gradient centrifugation, phagocytic cell removal, and fluorescence-activated cell sorting. Isolated thrombocytes produced CD41⁺ EVs (CD41⁺ EVs), and the CD41⁺ EVs also expressed CD9. Microarray analysis revealed that CD41⁺ EVs contain many microRNAs. Macrophage lines (RAW264.7) phagocytosed CD41⁺ EVs, and their phagocytosis and migration activity were suppressed. Microarray analysis also revealed that EVs altered gene expression in macrophages. These data indicated that the CD41⁺ EV was a carrier of microRNAs produced from thrombocytes and affected the cell characteristics of the received cells. Therefore, the CD41⁺ EVs of avians worked as a communication tool.