Laboratory evaluation of platelet function by a simple and reliable in vitro method is crucial to understand the critical role of platelets during hemostasis and thrombotic complications of cardiovascular disease. This process is very challenging, since platelets can be easily activated during blood drawing and samples must be processed in a timely manner to avoid spontaneous platelet activation. An in vitro quantitative determination of platelet aggregation by the light transmittance aggregometry (LTA) and the important role of adenosine diphosphate (ADP) during platelet aggregation were first described by Born in 1962 [1]. Despite some important limitations, LTA (turbidimetric assay, optical aggregometry, or conventional aggregometry) with platelet-rich plasma (PRP) is still considered as the “gold standard assay” for platelet function measurement.

In the landmark study by Born, it was reported that PRP was stirred at a rate of 1000 rotations per minute using a small polyethylene-covered iron rod, and the extent of decrease in optical density following platelet aggregation was proportional to the concentration of the ADP added. It was further demonstrated that the addition of adenosine monophosphate at similar concentrations reversed the platelet aggregation induced by ADP [1]. This study laid the foundation for the development of in vitro methods of platelet function testing (PFT), which were widely used during the assessment of bleeding disorders. It was further used in experiments to identify important targets to inhibit platelet function and to develop antiplatelet agents directed against these targets. Currently, these antiplatelet agents such as aspirin, P2Y₁₂ receptor inhibitors, and glycoprotein (GP)IIb/IIIa inhibitors constitute a major pharmacological therapy in the treatment of high-risk coronary artery disease patients.