H gly pro arg pro oh acetate salt gprp

Whole blood (WB) was collected in 40 µg/mL corn trypsin inhibitor (CTI; Haematologic Technologies, Essex Junction, VT, USA) or 100 µM D‐Phe‐Pro‐Arg‐CMK (PPACK; Haematologic Technologies) from healthy donors who self‐reported to be free of oral medication for at least 10 days before phlebotomy. All blood was collected under approval of the University of Pennsylvania’s Institutional Review Board. WB was treated with various reagents: 5 mM H‐Gly‐Pro‐Arg‐Pro‐OH acetate salt (GPRP; Bachem Americas, Vista, CA, USA), 50 µM acetylsalicylic acid (ASA; Sigma‐Aldrich, St Louis, MO, USA), or 100 µM MRS‐2179 (Tocris, Minneapolis, MN, USA). Platelets were labeled with an AF488 mouse anti‐human CD61 antibody (Bio‐Rad Laboratories, Hercules, CA, USA) at 20 µg/mL, P‐selectin was labeled with AF647 anti‐human CD62P (BioLegend, San Diego, CA, USA) at 2 µg/mL. AF647‐conjugated fibrinogen was added to WB at 12.5 µg/mL to observe fibrin formation.