Platelet storage media change the expression characteristics of the platelet-derived microparticles

Activated platelets shed microparticles in vivo and definitely in vitro upon aging under storage. Studies about the platelet-derived microparticles (PMPs) produced in different storage media of PC were very limited. The aim of this research was to compare some surface molecules of these microvesicles in dissimilar microenvironments; plasma and the candidate medium for the platelet concentrate, Composol. Thirty units of PCs were prepared from Iranian Blood Transfusion Organization. Each unit was divided into two portions. In one of the portions, plasma was replaced with Composol using a connecting device instrument. MPs were isolated from PC and the levels of PS exposure (the annexin-binding capacity) and binding to vWF were surveyed on their surface using ELISA and flow cytometry techniques. The levels of PS exposure were increased on MPs during 7 days storage in the both media but the differences were not significant (P value >0.05). In addition, binding of PMP to vWF was declined during storage. The binding capabilities of PMP were significantly higher in Composol than that of plasma at the day 4 or 7 of storage (P value = 001). It seemed that the binding of PMPs to vWF was affected from the storage media of PC (plasma and Composol) but PS exposure was not affected from the type of storage media.