Decline in platelet microparticles contributes to reduced hemostatic potential of stored plasma

Abstract

Introduction In an effort to administer life-saving transfusions quickly, some trauma centers maintain thawed plasma (TP). According to AABB, TP is approved for transfusion for up to five days when stored at 1 – 6 °C. However, the alterations in microparticles (MP) contained in the plasma, which are an integral component of plasma’s hemostatic capacity, are not well characterized. We report on MP changes in TP between its initial thaw (FFP-0) and five days (FFP-5) of storage. Materials and Methods FFP units (n=30) were thawed at 37 °C and kept refrigerated for five days. Phenotypes of residual cells, which include platelets, erythrocytes, leukocytes, monocytes, endothelial cells, and MP counterparts of each cell type, were analyzed by flow cytometry. Functional assays were used for MP procoagulant activity, plasma thrombin generation, and clotting properties (thromboelastography). Results In FFP-0 the majority (94%) of residual cells were platelets, along with significant levels of platelet MPs (4408×103/L). FFP-5 showed a decline in MP count by 50% (p<0.0001), and procoagulant activity by 29% (p<0.0001). FFP-5 exhibited only 54% (p<0.0001) of the potential for thrombin generation as FFP-0, while thromboelastography indicated a slower clotting response (p<0.0001) and a longer delay in reaching maximum clot (p<0.01). Removal of MP by filtration resulted in reduced thrombin generation, while the MP replacement restored it. Conclusions Decline in MP with storage contributes to FFP-5’s reduced ability to provide the hemostatic potential exhibited by FFP-0, suggesting the presence of platelet MPs in freshly TP may be beneficial and protective in the initial treatment of hemorrhage.

Platelet Microvesicles (Microparticles) in Cardiac Surgery

“…The resulting decline in procoagulant activity was 29%, indicating that PMV numbers decrease in vitro and contribute to in vivo coagulation. 10 The same study also demonstrated that removal of PMV by filtration results in reduced thrombin generation, and that restoration of PMV into the infusion increased the ability for coagulation. The cause of PMV decline in vitro is only speculated; Matijevic et al suggests that extacellular phospholipases may degrade the microvesicles to sub-detectable volumes or that microvesicle coupling to other microvesicles or platelets occurs, forming larger aggregates.…”

“…Platelet microvesicles (PMV) are the most abundant in normal plasma. 7,10 PMV have an important role in the initiation and propagation of coagulation, providing a key focus for hematologic research to improve the safety of cardiac surgery. Their discovery occurred when the clotting time of blood was prolonged following high-speed centrifugation during which PMV became separated from platelet-dense serum, suggesting that PMV enhance coagulation.…”

Never-frozen liquid plasma blocks endothelial permeability as effectively as thawed fresh frozen plasma

“…Under these conditions, obtained TEG tracings represent fibrin clot generated from plasma clotting factors/inhibitors and residual platelets but without red blood cells or leukocytes given that their presence in plasma products is negligible. 4,15 Statistical Analysis For in vitro permeability assays, data were analyzed using one-way analysis of variance for single time point studies and two-way analysis of variance for time course studies. When significant, an appropriate multiple comparison Holm-Sidak method was applied.…”

Proteomic analysis of microvesicles from plasma of healthy donors reveals high individual variability

“…In addition, these MVs play a role as membrane surfaces on which components of the coagulation protease cascade can assemble [12][13][14]. In this context, the plasma MV fraction has been implicated in some adverse transfusion-related events [15,16]. For this reason, it is essential to design and establish quality controls for circulating plasma MVs.…”