Effects of Cryopreservation on Microparticles Concentration, Procoagulant Function, Size Distribution, and Morphology.

BACKGROUND Research on microparticles is rapidly evolving and has extended to the field of many diseases. It is unclear whether microparticles can be stored frozen. In this study, our goal was to verify whether cryopreservation had an effect on the properties of the microparticles. MATERIAL AND METHODS We obtained C57BL/6J mouse-derived microparticles by grinding and gradient centrifugation. The specimens were divided into 2 groups: without dimethyl sulfoxide and with dimethyl sulfoxide. The microparticles were then stored at 25°C, 4°C, -20°C, -80°C, and -196°C for 0.5 days, 1 day, 3 days, 5 days, and 7 days. We tested whether the concentration, coagulation function, diameter distribution, and morphology of the microparticles in the 2 groups changed compared to those of a fresh sample. RESULTS We discovered that the concentrations of total microparticles, annexin V-positive microparticles, and brain-derived microparticles changed with freezing. The coagulation function, morphology, and size distribution of the microparticles were also affected by cryopreservation. Finally, there was no difference in the effects of cryopreservation on microparticles between the dimethyl sulfoxide group and the dimethyl sulfoxide-free group. CONCLUSIONS This study suggests that cryopreservation has diverse effects on microparticles within 1 week and that dimethyl sulfoxide has no protective effect on cryopreserved microparticles. Therefore, microparticles should be used fresh for future studies, and they should not be cryopreserved with or without dimethyl sulfoxide.