A simple adhesion assay for studying interactions between platelets and endothelial cells in vitro

Cell adhesion plays a key role during various physiological and pathological processes. Many studies have been performed to understand the interaction of platelets with endothelial cells (ECs) during the past decades. Modulation of their interaction has been shown to be therapeutically useful in thrombotic diseases. Some methods of labeling platelets such as counting and radiolabeling have been applied in the study of the platelets-ECs interaction, but these methods did not obtain full approval. A rapid, simple and sensitive assay for platelets-ECs interaction was developed in this paper. Platelets were labeled with Sudan Black B (SBB) before adding to confluent ECs monolayer. Non-adherent platelets were removed by washing with PBS. The adherent platelets were lysed with dimethylsulfoxide (DMSO) and the absorbance was recorded at 595 nm by spectrophotometer. A linear correlation was observed between the absorbance of SBB and the number of platelets. By employing the SBB method, the influence of heparin on platelets-ECs interactions was observed. Heparin (3-100 units/mL) obviously reduced platelets adhering to ECs in a concentration-dependent manner.