Isolated platelets are internalized by hepatocytes. (A) Activated platelets (green) were labeled with CellTracker green CMFDA and incubated under serum-free conditions with HepG2 cells. Fluorescent images were taken after 5 minutes, 30 minutes, and 1 hour. HepG2 cells were stained for actin (red), and nuclei were stained with DAPI (blue). Original magnification ×200. Scale bar, 20µm. (B) (i) High magnification fluorescence image of single platelets (arrows) attached to the HepG2 cell membrane after 30 minutes of coculturing. Original magnification ×400. Scale bar, 10 µm. (ii) Electron micrograph of a single platelet attached to a HepG2 membrane. Original magnification ×9700; scale bar, 1 µm. (C) Confocal microscopy image of HepG2 cells that have been exposed to platelets. Images were captured after 1-hour incubation with CMFDA-labeled platelets (green). The HepG2 cells were stained for actin (red). The image shows a slice from the middle of the confocal stack. Original magnification ∼400. Scale bar, 20 μm. (D) Transmission electron microscopy imaging of hepatocytes that have been exposed to platelets. (i) Lower-magnification (×9700) image of a group of HepG2 cells showing platelets within hepatocytes indicated by arrows. Scale bar, 5 µm. (ii) High-magnification image of the same region (×24 500) shows the internalized platelet (*) surrounded by endoplasmic reticulum and located close to the nucleus (#). The arrow indicates the plasma membrane of the HepG2 cell. Scale bar, 1 µm. Images are representative of at least 3 independent experiments. (E) Transmission electron microscopy imaging of mouse liver 1 hour after hepatectomy. (i) A section of liver tissue taken from a mouse that underwent a 70% hepatectomy. The arrow indicates a platelet within a hepatocyte. Original magnification ×5800. Scale bar, 10 µm. (ii) High-magnification image of the same region (×33 000) shows the internalized platelet by the hepatocyte. Scale bar, 1 µm.