Whole blood samples were centrifuge

Whole blood samples were centrifuged for 5 min at 200 × g to obtain platelet-rich plasma. The platelet-rich plasma was washed once with PBS-EDTA/BSA buffer (1× phosphate-buffered saline (PBS) containing 10 mM EDTA and 0.2% (wt/vol) bovine serum albumin (BSA) solution), and then the platelets concentration was adjusted to 1×108 per mL. The 10 μL platelet suspension was incubated with 5 μL FITC-conjugated blood group antibody (or FITC-conjugated anti-IgG as isotype control) and 5 μL R-PE-conjugated anti-CD41 in 100 μL PBS-EDTA/BSA buffer for 20 minutes at room temperature. Then the cells were washed once and resuspended in 400 μL PBS solution containing 1% paraformaldehyde for fluorescent analysis.