Whole blood platelet aggregation in humans and animals: a comparative study

Area of Science:

• Biomedical Engineering
• Hematology
• Comparative Physiology

Background:

• Interspecies differences in platelet activity are crucial for cardiovascular device evaluation.
• Limited characterization of platelet response to agonists across species.

Purpose of the Study:

• To measure and compare platelet aggregation and adenosine triphosphate (ATP) release in response to various agonists in human, dog, and calf blood.
• To identify optimal agonists for interspecies platelet function studies.

Main Methods:

• Whole blood impedance lumi-aggregometry used to analyze platelet aggregation and ATP release.
• Blood samples from humans (n=19), dogs (n=19), and calves (n=7) were tested.
• Six agonists were used: collagen, ristocetin, arachidonic acid, thrombin, adenosine diphosphate (ADP), and epinephrine at varying concentrations.

Main Results:

• Collagen (1 microg/ml) and ADP (5, 10, 20 microM) induced aggregation and ATP release in all species.
• Canine platelets responded to all agonists; human platelets responded to all except epinephrine at specific doses.
• Bovine platelets showed limited response (collagen, ADP, thrombin), with significantly lower aggregation and ATP release compared to humans and dogs.

Conclusions:

• Significant interspecies variations exist in platelet reactivity to agonists.
• Collagen (1 microg/ml) and ADP (10 microM) are recommended for consistent whole blood platelet aggregation studies.
• Thrombin (1 U/ml) is the recommended agonist for adenosine triphosphate (ATP) release assays across species.