Figure 4. Platelets phagocytosis in different cells.

In (A) CFSE labeled porcine platelets (green) were mixed with pig hepatocytes, aortic endothelial cells and liver endothelial cells (stained by CellTracker™ Blue CMAC, blue), co-cultured for 1 h at 37°C. No phagocytosis was observed (confocal microscopy×400).In (B), CFSE labeled baboon platelets (green) were mixed with pig hepatocytes, aortic endothelial cells and liver endothelial cells (stained by CellTracker™ Blue CMAC, blue), co-cultured for 1 h at 37°C. Platelet internalization by hepatocytes, aortic endothelial cells and liver endothelial cells was absent, mild and strong, respectively (confocal microscopy ×400). In (C), baboon platelets (labeled by CFSE, green) are rapidly internalized by pig liver endothelial cells (stained by CellTracker™7-amino-4-chloromethylcoumarin, blue) (confocal microscopy ×400). The left panel shows the sequential section analysis of a single endothelial cell that has internalized platelets, the sections go from top to bottom. The right panel shows the analysis of one section with simultaneous indication of location of platelets within the endothelial cell, indicating that these are clearly internalized and not on the cell surface.