Animal models for studies on cold-induced platelet activation in human beings

When human platelets are chilled below about 20 degrees C, they spontaneously activate, a phenomenon that limits their storage lifetime. We have previously shown that this activation in chilled human platelets is associated with passage through a lipid phase transition. Because animal models are necessary for investigating methods for cold storage of platelets, it is essential to determine whether such phase transitions and chilling-induced activation are found in these models. In this study we examined platelets from some commonly used animal models-pigs, rhesus monkeys, mice, dogs, and rabbits. Using Fourier transform infrared spectroscopy (FTIR), we detected the thermotropic membrane phase transition in intact platelets and assessed the morphologic response of the platelets to chilling. Statistical analysis of both FTIR and shape change show that of the animal models tested, pig platelets are most similar to human platelets. These studies suggest that pigs and pig platelets are the models of choice for the study of cold-induced platelet activation in human beings.