WGA is a probe for migrasomes

During cell migration, cells leave behind long tubular retraction fibers. Previously, we identified that vesicles with diameters up to 2 µm, which we called migrasomes, grow at the tips and intersections of retraction fibers 1 . We found that the migrasomes contain cytosol, which can be released into the extracellular environment or directly taken up by surrounding cells 1 . Therefore, we proposed that migrasomes may mediate cell–cell communications. We identified Tetraspanin4 (Tspan4) as a marker for migrasomes, and thus we can detect migrasomes in various types of cells and characterize the process of migrasome biogenesis. However, the limitations of using a fluorescently tagged marker protein for detection of an organelle are obvious. First, it is time consuming; transfection and expression of the marker protein takes at least 1 day before observation. Second, the transfections of many cells, especially many primary cells, are very difficult. For these cells, complicated transfection strategies (e.g., virus-mediated transfection) are required, which further increase the time and cost of migrasome detection. Finally, overexpression of fluorescently tagged protein always has the risk that the overexpressed marker protein may change the biogenesis of migrasomes, thus causing artifacts. Thus a rapid, easy, and non-interfering method is needed for detection of migrasomes.