[Establishment of a method for separating macrophage migrasomes].

Objective To establish an efficient method for isolating migrasomes from RAW264.7 macrophages and identifying these isolated migrasomes. Methods Scanning electron microscopy was used to observe the morphological characteristics of migrasomes produced by RAW264.7 cells. A 0.45 μm filter was employed for reverse filtration and elution to isolate the migrasomes. The morphological characteristics of the migrasomes were then observed using transmission electron microscopy. Western blot analysis was performed to determine the expression of characteristic markers of the migrasomes. The RNA carried by the migrasomes was analysed by using LabChip bioanalyzer. Results Scanning electron microscopy revealed that the migrasomes, with membranous structures, were attached to the tip or bifurcation of the retraction fiber formed in the tail of RAW264.7 cells. Transmission electron microscopy showed that the isolated migrasomes had a typical oval vesicle-like structure with wrinkled membrane surfaces. Western blot analysis confirmed the expression of the characteristic markers phosphatidylinositol glycan anchor biosynthesis class K (PIGK), epidermal growth factor domain-specific O-linked N-acetylglucosamine transferase (EOGT) and tetraspanin 4 (TSPAN4) in the migrasomes, while the EV (extracellular vesicle) markers tumor susceptibility gene 101 (TSG101) and Arabidopsis homolog of apoptosis-linked gene 2-interacting protein X (ALIX) were not detected. Furthermore, the isolated migrasomes were found to be rich in small RNA, which were approximately 25-200 nt in length. Conclusion A method for the extraction of well-structured and high quality migrasomes from macrophages is established.